mesa: Fix enum definition of CULL_VERTEX_EYE/OBJECT_POSITION
mesa: Fix enum definition of CULL_VERTEX_EYE/OBJECT_POSITION

In converting to using the Khronos XML, I found that our XML had these two
swapped, and the text spec agreed.

Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler