nir: add nir_function::pass_flags

convenience, asahi will stash stuff here.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Konstantin Seurer <konstantin.seurer@gmail.com>
Reviewed-by: Mary Guillemard <mary.guillemard@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32382>

src/compiler/nir/nir.h

@@ -3661,6 +3661,9 @@ typedef struct nir_function {
    const struct glsl_type **subroutine_types;
 
    int subroutine_index;
+
+   /* A temporary for passes to use for storing flags. */
+   uint32_t pass_flags;
 } nir_function;
 
 typedef enum {