nir: Properly invalidate metadata in nir_opt_remove_phis().

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Eduardo Lima Mitev <elima@igalia.com>
Cc: mesa-stable@lists.freedesktop.org
(cherry picked from commit 59bbe2681b)

src/glsl/nir/nir_opt_remove_phis.c

@@ -92,6 +92,11 @@ remove_phis_impl(nir_function_impl *impl)
 
    nir_foreach_block(impl, remove_phis_block, &progress);
 
+   if (progress) {
+      nir_metadata_preserve(impl, nir_metadata_block_index |
+                                  nir_metadata_dominance);
+   }
+
    return progress;
 }