mesa/main: validate name syntax for array variables only

mesa/main: validate name syntax for array variables only

From ARB_program_interface_query:

 "Note that if an interface enumerates a single active resource list
 entry for an array variable (e.g., "a[0]"), a <name> identifying
 any array element other than the first (e.g., "a[1]") is not
 considered to match."

It doesn't apply to arrays of interface blocks but just to array
variables.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>