misc nx-X11/programs/Xserver/{hw/nxagent,miext,render}/: move code around so that we can drop nx-X11/programs/Xserver/render/miglyph.c (and by extension nx-X11/programs/Xserver/hw/nxagent/NXmiglyph.c.)

This is essentially a bastardized cross/backport of these X.Org commits - based
on our current architecture:

commit 4b14c9a9cd2033d3839c4ba364d41ab4c4b198ab
Author: Eric Anholt <eric@anholt.net>
Date:   Fri Oct 19 16:34:54 2007 -0700

    Replace calls to Glyphs screen hook with CompositeGlyphs and remove dead code.

    Not all of the DDX/miext Glyphs hook implementations have been removed, but
    they should be.

and

commit 2251572062b2c25643671b8d5070de1c3f7ae976
Author: Aaron Plattner <aplattner@nvidia.com>
Date:   Fri Oct 26 15:13:50 2007 -0700

    Restore the CompositeGlyphs -> ps->Glyphs -> miGlyphs callchain to allow acceleration architectures to wrap above miGlyphs.

Conflicts:
	nx-X11/programs/Xserver/render/miglyph.c
	nx-X11/programs/Xserver/render/mipict.h
	nx-X11/programs/Xserver/render/picture.c