nir/lower_int64: mark all metadata as dirty

v2: use nir_metadata_preserve
    preserve metadata in case of !progress

Fixes: 074f5ba0b5
       "nir: Add a simple int64 lowering pass"
Signed-off-by: Karol Herbst <kherbst@redhat.com>

src/compiler/nir/nir_lower_int64.c

@@ -279,6 +279,9 @@ lower_int64_impl(nir_function_impl *impl, nir_lower_int64_options options)
       }
    }
 
+   if (progress)
+      nir_metadata_preserve(impl, nir_metadata_none);
+
    return progress;
 }