New composite glyphs code uses the updated glamor program
infrastructure to create efficient shaders for drawing render text.

Glyphs are cached in two atlases (one 8-bit, one 32-bit) in a simple
linear fashion. When the atlas fills, it is discarded and a new one
constructed.

v2: Eric Anholt changed the non-GLSL 130 path to use quads instead of
two triangles for a significant performance improvement on hardware
with quads. Someone can fix the GLES quads emulation if they want to
make it faster there.

v3: Eric found more dead code to delete

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Eric Anholt <eric@anholt.net>