many functions are almost identical to dix. Mark the minimal changes.

The only difference to the dix version was a fprintf if compiled with
-D TEST.

Attributes GH PR #865: https://github.com/ArcticaProject/nx-libs/pull/865

no function change

Attributes GH PR #864: https://github.com/ArcticaProject/nx-libs/pull/864

NXxvdisp.c only exists to set/unset nxagentXvTrap before/after
dispatch. There's no need to duplicate the original code. We now
rename the original dispatch functions and call them in our dispatch
code.

Also drop check for sun and cygwin, as they never appeared in xorg
upstream code.

Attributes GH PR #863: https://github.com/ArcticaProject/nx-libs/pull/863

by calling the upstream function from dix/dispatch.c

remove ~80 duplicate lines

by calling upstream version from dispatch.c

Attributes GH PR #861: https://github.com/ArcticaProject/nx-libs/pull/861

instead of including it and creating NXextension.o we can simply use
the dix version. There are no NX specials anymore.

Attributes GH PR #859: https://github.com/ArcticaProject/nx-libs/pull/859

instead of having an identical copy in nxagent_miShmPutImage

instead of having an own (identical) copy

Attributes GH PR #856: https://github.com/ArcticaProject/nx-libs/pull/856

The only left code was nxagentCheckum() which was not compiling anyway.

Attributes GH PR #870: https://github.com/ArcticaProject/nx-libs/pull/870

With the previous commits this file finally becomes obsolete.

This backport of a 2013 Xorg fix changes miext/damage.c so that the
text functions (damageText, damage{Poly,Image}Text{8,16}) finally are
very similar to the changes that NX introduced in 2007 with
nxagent-3.0.0-28.

Fun fact: the original freedesktop bug mentioned below is from 2005
and the fix came in 2013...

Next commit will be the complete drop of NXdamage.c.

  commit 0f3f8e4295d4c05f33b93e0ffd2f6f8cd5759bf7
  Author: Adam Jackson <ajax@redhat.com>
  Date:   Wed Aug 21 11:13:11 2013 -0400

    damage: Don't rewrite Text ops to GlyphBlt ops

    There's no particularly good reason to, and it breaks Xnest.

    Bugzilla: http://bugs.freedesktop.org/2454Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Adam Jackson <ajax@redhat.com>

f0ba303d errornously added the "else"
which had been explicitly removed in NX 3.0.0-28 with this comment:

- Changed damage's GCOps functions drawing text. This was needed be-
  cause the original functions didn't call agent GCOps if the drawable
  was registered for damage events.

Attributes GH PR #858: https://github.com/ArcticaProject/nx-libs/pull/858

add a callback to determine the starting window.

Our version only adds some commented code, so it is not really
necessary. But it is cleaner to handle it that way.

Attributes GH PR #851: https://github.com/ArcticaProject/nx-libs/pull/851

Backport of this commit:

  commit 7ba7085b4f01f3cd72008712a5333ea3f0edfd88
  Author: walter harms <wharms@bfs.de>
  Date:   Sat Oct 28 19:14:22 2017 +0200

    AuRead.c: remove redundant null check on calling free()

    this removes simply unneeded code from XauReadAuth
Signed-off-by: Walter Harms <wharms@bfs.de>
Reviewed-by: Daniel Martin <consume.noise@gmail.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>