doxygen: Remove src/mesa/shader/ references
Mesa has not had a src/mesa/shader/ folder since Mesa 7.9 removed it
in October 2010, as part of a revised GLSL compiler written by Intel.
Remove doxygen/shader.doxy and consequential changes made throughout.
In addition to removing an unnecessary Doxygen doxyfile, this change also
avoids a bug in the consolidated Doxygen output caused by
doxygen/shader.doxy inadvertently overwriting doxygen/swrast.tag via its
GENERATE_TAGFILE setting.
This bug depended upon the specific order each *.tag was built.
Signed-off-by: Rhys Kidd <rhyskidd@gmail.com>
Acked-by: Emil Velikov <emil.velikov@collabora.com>