Backported from X.org, patch found in janitor cleanup commit...

 commit 8ba0ca32a63c532f128bdca7f1bf982cab8e12be
 Author: Paulo Cesar Pereira de Andrade <pcpa@mandriva.com.br>
 Date:   Wed Jan 28 20:31:42 2009 -0200

 Backported from X.org (libX11). Host.c has mainly been copied over from
 libX11, contaning 7db7451 as the top commit (which also contains the
 greatest change and silences the resp. compiler warning.

 commit 7db74514e454d3fc4ff70aa08ddac66bfffda4dd
 Author: Alan Coopersmith <alan.coopersmith@oracle.com>
 Date:   Tue Jul 23 22:18:46 2013 -0700

    Refactor common code from XAddHost & XRemoveHost into single function

    On the Xlib side, the only real difference is the mode flag we send
    to the server with the address, so just make that an argument to the
    function with the common code for packing the address into the request.

    (Aside from labels, gcc 4.7.2 generates identical code before & after
     this change due to inlining, verified via diff of gcc -S output.)
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

  - Update XErrorDB to latest X.org version.
  - Install XErrorDB, XKeysymDB and Xcms.txt to /usr/{local/}share/nx/.
  - Assure that libNX_X11 finds those files at the
    named location.
  - Update debian/ packaging files.
  - Update nx-libs.spec packaging file.

Fixes ArcticaProject/nx-libs#153

Fixes ArcticaProject/nx-libs#105

We might better change all guard defines with the ones upstream is
using but for now this should also work.

use system libXext instead

 Note:

  - The "normal" way to inject CFLAGS (and CPPFLAGS) into nx-X11 builds is copying those
    options over into the variable CDEBUGFLAGS.
  - LDFLAGS have to be handed to nx-X11 via LOCAL_LDFLAGS.

 This change also includes a slight change in the nx-X11 build order.

 Old build order:

  Main Makefile:

      - [...]
      - libNX_X11
        + implicitly building nxcomp
        + implicitly building nxcompext
      - [...]
      - nxagent
        + implicitly building nxcompshad
      - [...]

 New build ordner:

  Main Makefile:

      - [...]
      - nxcomp
      - setup nx-X11 build env
        + cd nx-X11 && make BuildEnv
      - nx-X11/lib/*
      - nxcompext
      - nxcompshad
      - [...]
      - nxagent
      - [...]

 Fixes ArcticaProject/nx-libs#141
 Fixes X2GoBTS#84

 Note:

  - The "normal" way to inject CFLAGS (and CPPFLAGS) into nx-X11 builds is copying those
    options over into the variable CDEBUGFLAGS.
  - LDFLAGS have to be handed to nx-X11 via LOCAL_LDFLAGS.

 This change also includes a slight change in the nx-X11 build order.

 Old build order:

  Main Makefile:

      - [...]
      - libNX_X11
        + implicitly building nxcomp
        + implicitly building nxcompext
      - [...]
      - nxagent
        + implicitly building nxcompshad
      - [...]

 New build ordner:

  Main Makefile:

      - [...]
      - nxcomp
      - setup nx-X11 build env
        + cd nx-X11 && make BuildEnv
      - nxcompext
      - nxcompshad
      - nx-X11/lib/*
      - [...]
      - nxagent
      - [...]

 Fixes ArcticaProject/nx-libs#141
 Fixes X2GoBTS#84

This required for successful linking of libXrender against libNX_X11.

Port from libXfixes commit b031e3b60fa1af9e49449f23d4a84395868be3ab We
need this here to enable linking of current libXrender against
libNX_X11 instead of the system's libX11

The original implementation of this function (libX11 commit
9f5d83706543696fc944c1835a403938c06f2cc5) uses xcb stuff which we do
not have in libNX_X11. So we take a workaround from another lib. This
workaround had been added temporarily to a couple of X extension libs,
see
e.g. https://lists.x.org/archives/xorg-devel/2013-July/036763.html.

To enable linking of a current libXrender libNX_X11 needs that symbol.

This is a (manual) backport of the following upstream libX11 commit
available at
https://cgit.freedesktop.org/xorg/lib/libX11/commit/src/XlibInt.c?id=4a060f993bf676cf21ad9784e010f54134da7b40:

     Commit: 4a060f993bf676cf21ad9784e010f54134da7b40
     Author: Peter Hutterer <peter.hutterer@who-t.net>
     Date: Mon, 17 Oct 2011 09:45:15 +1000
     Subject: Add _XGetRequest as substitute for GetReq/GetReqExtra

To allow for suspend/resume NX has changed _XReadEvents() and
_XIOError(). _XIOError() does not simply exit but returns. And
_XReadEvents() returns after _XIOError(). But as the original
_XReadEvents() is supposed to block until at least one event is there
calling functions are not prepared for situations where no event is
available. These calling functions have to check that condition.,

Some of the calling functions already had that check but the
UnlockDisplay() call was missing.

Fixes https://github.com/ArcticaProject/nx-libs/issues/118

To allow for suspend/resume NX has changed _XReadEvents() and
_XIOError(). _XIOError() does not simply exit but returns. And
_XReadEvents() returns after _XIOError(). But as the original
_XReadEvents() is supposed to block until at least one event is there
calling functions are not prepared for situations where no event is
available. These calling functions have to check that condition.,

Some of the calling functions already had that check but the
UnlockDisplay() call was missing.

Fixes https://github.com/ArcticaProject/nx-libs/issues/118

nx-X11/programs/Xserver: Include nxcomp{,ext,shad} headers like one would do with system-wide shared libraries.

  include/extensions: Xag.h, Xagsrv.h, Xagstr.h
  Xserver/Xext: appgroup.c, appgroup.h
  lib/Xext: XAppgroup.c

  include/extensions: Xcup.h, Xcupstr.h,
  Xserver/Xext: cup.c
  lib/Xext: cup.c

  include/extensions: Xdbe.h
  Xserver/Xext: Xdbe.c

  Xserver/Xext:  dgaproc.h, xf86dga.c, xf86dga2.c, xf86dgaext.h

  include/extensions: Xevie.h, Xeviestr.h
  include/extensions: XEVI.h, XEVIstr.h
  Xserver/Xext: EVI.c, EVIstruct.h, sampleEVI.c
  lib/Xext: XEVI.c

  include/extensions: fontcache.h, fontcacheP.h, fontcachstr.h
  Xserver/Xext: fontcache.c

  include/extensions: lbxbuf.h, lbxbufstr.h, lbxdeltastr.h, lbximage.h, lbxopts.h, lbxstr.h, lbxzlib.h
  lib/Xext: XLbx.c

  include/extensions: multibuf.h, multibufst.h
  lib/Xext: XMultibuf.c
  Xserver/Xext: mbuf.c, mbufbf.c, mbufpx.c

  include/extensions: xf86vmode.h, xf86vmstr.h
  Xserver/Xext: vidmodeproc.h, xf86vmode.c

  lib/Xext: MITMisc.c
  Xserver/Xext: mitmisc.c

  Xserver/Xext: xf86misc.c, xf86miscproc.h

  Xserver/XTrap: xf86XTrapModule.c, xtrapddmi.c, xtrapdi.c, xtrapdiswp.c, xtrapditbl.c
  include/extensions: xtrapbits.h xtrapddmi.h xtrapdi.h xtrapemacros.h xtraplib.h xtraplibp.h xtrapproto.h
  Fixes: ArcticaProject/nx-libs#116
  X.org: https://cgit.freedesktop.org/xorg/xserver/commit/?id=cbc20d92de92aad5ca240310a9156ccf97c24a01

  Plus: Drop various Imake'ish defines where not needed anymore.

 The var is not defined anymore and the libXinerama code has been removed
 some time ago.

library clean-up: Don't build libNX_Xinerama anymore. Use system's libXinerama shared library. (Fixes ArcticaProject/nx-libs#49).

 This commit goes along with a patch from Ulrich Sibiller who managed to
 move the Xinerama awareness for NX sessions into the Xserver code. This
 makes Xinerama support for NX in libNX_Xinerama.so obsolete.

 Fixes ArcticaProject/nx-libs#49

library clean-up: Don't build libNX_Xtst anymore. Use system's libXtst shared library. (Fixes ArcticaProject/nx-libs#32).

X11/nx-X11 clear-up: More places where we need to explicitly distinguish between X11 and nx-X11 namespace regarding header include paths.

 In the process of building nxagent against more and more system-wide installed
 X.org libraries, we come to the limit of including structs from this (bundled
 nx-X11) and that (system-wide X.Org) library.

 This commit introduces a clear namespace separation of headers provided by
 nx-X11 and headers provided by X.Org. This approach is only temporary as we
 want to drop all nx-X11 bundled libraries from nx-libs.

 However, for a while we need to make this separation clear and also ship
 some reduced fake X.Org headers that avoid pulling in libX* and libNX_X*
 symbols at the same time.

 This patch has been tested on Debian jessie and unstable and requires no
 overall testing on various distros and distro versions, as we finally will
 drop all libNX_X* libraries and build against X.org's client libs.

 For now, this hack eases our development / cleanup process.

 Due to C arithmetic conversion rules we must use an unsigned constant (or a
 cast) to perform the multiplication using unsigned arithmetic.

 Fixes ArcticaProject/nx-libs#55.

 Author: Emanuele Giaquinta <emanuele.giaquinta@gmail.com>
Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>
 Rebased against NX: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>