mesa: Remove commas at end of enumerator lists.

mesa: Remove commas at end of enumerator lists.

Fixes these build errors on OpenBSD 5.3.

In file included from ../../src/mesa/main/errors.h:47,
                 from ../../src/mesa/main/imports.h:41,
                 from ../../src/mesa/main/ff_fragment_shader.cpp:32:
../../src/mesa/main/mtypes.h:3286: error: comma at end of enumerator list
../../src/mesa/main/mtypes.h:3296: error: comma at end of enumerator list
../../src/mesa/main/mtypes.h:3303: error: comma at end of enumerator list
../../src/mesa/main/mtypes.h:3356: error: comma at end of enumerator list

Signed-off-by: Vinson Lee <vlee@freedesktop.org>