[server-21.1-branch] Backport glamor fixes.

This is a backports of all of my merged MRs for GLES2 to xserver 21.1

List: !328 (merged) !914 (merged) !948 (merged) !1007 (merged) !1156 (merged) !1157 (merged) !1158 (merged) !1163 (merged) !1164 (merged) !1173 (merged) !1200 (merged) !1633 (merged)

Also it should fix Autotools build of Glamor GLX provider.

CC: @ofourdan