glsl: Switch ast_type_qualifier to the non-zeroing allocator.

All member variables of ast_type_qualifier are already being
initialized from its implicitly defined constructor, it's not
necessary to use rzalloc to allocate its memory.

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

src/glsl/ast.h

@@ -346,7 +346,7 @@ enum {
 };
 
 struct ast_type_qualifier {
-   DECLARE_RZALLOC_CXX_OPERATORS(ast_type_qualifier);
+   DECLARE_RALLOC_CXX_OPERATORS(ast_type_qualifier);
 
    union {
       struct {