mesa/formatquery: Added function to set 'unsupported' responses

mesa/formatquery: Added function to set 'unsupported' responses

The ARB_internalformat_query2 specification defines which is the
reponse best representing "not supported" or "not applicable" for
each <pname>.

Queries for unsupported features, targets, internalformats, combinations
of: target and internalformat, target and pname, pname and internalformat,
do not return an error but the corresponding 'unsupported' response.
We will use that response as the default answer.

For SAMPLES the 'unsupported' response is to not modify the 'params' buffer.

Reviewed-by: Dave Airlie <airlied@redhat.com>