glsl: Make sure that we don't put too many bitfields in ast_type_qualifier.

glsl: Make sure that we don't put too many bitfields in ast_type_qualifier.

We do some tests of qualifiers using a union containing an int and the
struct full of bitfields, so make sure the bitfields don't spill
outside the int.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>