radv: Wrap pragmas with __GNUC__ to fix MSVC

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7866>

src/amd/vulkan/radv_debug.c

@@ -860,10 +860,14 @@ radv_get_faulty_shader(struct radv_device *device, uint64_t faulty_pc)
 	mtx_lock(&device->shader_slab_mutex);
 
 	list_for_each_entry(struct radv_shader_slab, slab, &device->shader_slabs, slabs) {
+#ifdef __GNUC__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wshadow"
+#endif
 		list_for_each_entry(struct radv_shader_variant, s, &slab->shaders, slab_list) {
+#ifdef __GNUC__
 #pragma GCC diagnostic pop
+#endif
 			uint64_t offset = align_u64(s->bo_offset + s->code_size, 256);
 			uint64_t va = radv_buffer_get_va(s->bo);