mesa: Allow querying for GL_PRIMITIVE_RESTART_FIXED_INDEX under GLES 3

mesa: Allow querying for GL_PRIMITIVE_RESTART_FIXED_INDEX under GLES 3

GLES 3.0.0 spec introduces context state PRIMITIVE_RESTART_FIXED_INDEX
(2.8.1 Transferring Array Elements, page 26) which is not currently
possible to query using glGet*() funcs.

Fixes 4 dEQP tests:
* dEQP-GLES3.functional.state_query.boolean.primitive_restart_fixed_index_getboolean
* dEQP-GLES3.functional.state_query.boolean.primitive_restart_fixed_index_getinteger
* dEQP-GLES3.functional.state_query.boolean.primitive_restart_fixed_index_getinteger64
* dEQP-GLES3.functional.state_query.boolean.primitive_restart_fixed_index_getfloat

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>