glsl: Plumb through is_parameter to apply_type_qualifier_to_variable()

glsl: Plumb through is_parameter to apply_type_qualifier_to_variable()

This patch adds logic to allow the ast_to_hir function
apply_type_qualifier_to_variable() to tell whether it is acting on a
variable declaration or a function parameter.  This will allow it to
correctly interpret the meaning of "out" and "in" keywords (which have
different meanings in those two contexts).

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>