mesa: glGetProgramResourceLocation

mesa: glGetProgramResourceLocation

Patch adds required helper functions to shaderapi.h and
the actual implementation.

corresponding Piglit test:
   arb_program_interface_query-resource-location

The added functionality can be tested by tests for following
functions that are refactored by later patches:

   GetAttribLocation
   GetUniformLocation
   GetFragDataLocation

v2: code cleanup, changes to array element
    syntax checking (Ilia Mirkin)

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Martin Peres <martin.peres@linux.intel.com>