Xserver/include/protocol-versions.h: Switch to having an Xserver-specific header file containing all use protocol versions.

Attributes GH PR #172: https://github.com/ArcticaProject/nx-libs/pull/172
Reviewed by: Mihai Moldovan <ionic@ionic.de>  -- Fri Jul  1 00:38:00 CEST 2016
Reviewed by: Ulrich Sibiller <uli42@gmx.de>  -- Fri Jul  1 00:38:00 CEST 2016

  o Install nxagent/nxproxy executables into multi-arch path.
  o Fake libNX_X11.so* as $LIBDIR/nx-X11/libX11.so*.
  o Allow injecting different $NXAPP containing the executable name.

  o For e.g. x2goagent this requires the following changes:

    - Move x2goagent symlink from /usr/lib/x2go/bin/x2goagent to
      $LIBDIR/nx/bin/x2goagent
    - Replace /usr/bin/x2goagent by a two-liner...

    ```
    #!/bin/sh

    export NXAPP=x2goagent
    nxagent
    ```

Attributes GH PR #175: https://github.com/ArcticaProject/nx-libs/pull/175

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

use system libXext instead

Attributes GH PR #152: https://github.com/ArcticaProject/nx-libs/pull/152
Reviewed by: Vadim Troshchinskiy <vadim@qindel.com>  -- Fri, 01 Jul 2016 14:55:00 +0200

Attributes GH PR: https://github.com/ArcticaProject/nx-libs/pull/151
Self-reviewed: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>  -- Fri, 01 Jul 2016 14:03:44 +0200

debian/*.dirs: Don't create directories in the Debian package. All handled well by the upstream Makefile.

 ... detected by Debian's lintian tool.

debian/control: Drop various not-used-anymore libNX_* related packages. Add B:/R: to libnx-x11-{6,dev,6-dbg) to uninstall those package when upgrading to nx-libs 3.6.x.

roll-tarball.sh: Don't ship doc/X11-symbols/ in the lite (proxy-only) tarball derived from the nx-libs code tree.

debian/rules: Don't attempt at removing $(CURDIR)/.preserve/. Not needed anymore since we removed the CODE-REDUCTION_* hacks from debian/rules.

Attributes GH PR #150: https://github.com/ArcticaProject/nx-libs/pull/150
Reviewed by: Vadim Troshchinskiy <vadim@qindel.com>  -- Fri, 01 Jul 2016 04:33:22 -0700

 Note: This breaks building on ancient Linux distro versions, e.g. Ubuntu
 10.04 LTS.

 For details see:
 http://man7.org/tlpi/code/faq.html#use_default_source

Attributes GH PR #148: https://github.com/ArcticaProject/nx-libs/pull/148
Reviewed by Vadim Troshchinskiy <vadim@qindel.com>  -- Fri, 01 Jul 2016 03:12:26 -0700

Attributes GH PR #149: https://github.com/ArcticaProject/nx-libs/pull/149
Reviewed by Vadim Troshchinskiy <vadim@qindel.com>  -- Fri, 01 Jul 2016 02:02:49 -0700

 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

debian/libnx-x11-6.symbols: Update symbols (added: _XEatDataWords@Base 3.5.99.0, _XGetRequest@Base 3.5.99.0).

Attributes GH PR #146: https://github.com/ArcticaProject/nx-libs/pull/146
Reviewed by: Vadim Troshchinskiy <vadim@qindel.com>  -- Thu, 30 Jun 2016 06:30:46 -0700