Fixes: ArcticaProject/nx-libs#572

Fixes ArcticaProject/nx-libs#572

as reported by valgrind

Should avoid copy-constructing objects again.

nxcomp/src/Log.cpp: don't confuse users with useless warning messages in case that a log line append operation was requested, but the message level has lower precedence than the current log filter.

Especially don't flush data out mid-append.
Doing so will lead to the next append operation failing.

Should fix messages queuing up indefinitely (until they are discarded at
program termination, at least) and missing messages in general.

Fixes: ArcticaProject/nx-libs#577
Fixes: ArcticaProject/nx-libs#611

Also handle errors due to missing buffers gracefully.

This error is surprisingly easy to trigger, so we should make sure that
the program does not crash.

Was dropped erroneously in cec31e2f.

Besides that being a useless construct to begin with, not all shells
even support parameters to echo. Nuke that abomination from or^Wthe
repository.

This should get rid of the infamous "800x600 screen size" issue
reproduced in X2Go whole display setups.

Fixes RPM builds building libNX_X11 with poll() support, even though we
explicitly disable it using --disable-poll in the main Makefile.

Fixes: ArcticaProject/nx-libs#540

nx-X11/extras/Mesa.patches_6.4.2/4002_no-special-glx-memfunctions.patch: include stdlib.h and string.h for memset, malloc and free prototypes.

Without that they are only implicitly defined - leading to build
failures on *SUSE.

I didn't mean to drop it in the first place in
07d30835 and
71bda0ed.

Dropping the sed hack was fine -  but we actually have to add these
flags to CDEBUGFLAGS as well.

Drop SHMNAME workaround again, it *is* defined in shmstr.h, which is actually header I was searching for.

nx-X11/programs/Xserver/Xext/shape.c: avoid pulling in Xlib in legacy mode via the _SHAPE_SERVER_ macro.

nx-X11/programs/Xserver/Xext/shape.c: pull in shapestr.h for legacy Xext proto versions, since shape.h would pull in Xlib.

Especially don't add linking flags willy-nilly.

Legacy Xext proto versions are automatically detected by the main
Makefile.

This reverts commit cc47066b.

This package is actually already depended upon.

shmproto.h must be in some other package. Investigating.

Automake older than version 1.11 does not support dist-xz. No workaround
possible via a feature check, as far as I can tell.

Avoids errors like these (and of course also is a good idea in general):
[   36s] make -C nx-X11 BuildIncludes FONT_DEFINES= -DLEGACY_XFONT1
[   36s] make: invalid option -- D
[   36s] make: invalid option -- E
[   36s] make: invalid option -- G
[   36s] make: invalid option -- A
[   36s] Usage: make [options] [target] ...