8208671: Runtime, JFR, Serviceability changes to allow enabling -Wreorder

Reviewed-by: dholmes, hseigel

src/hotspot/share/oops/klass.cpp

@@ -191,9 +191,9 @@ void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word
 // Need to set the _java_mirror field explicitly to not hit an assert that the field
 // should be NULL before setting it.
 Klass::Klass(KlassID id) : _id(id),
+                           _java_mirror(NULL),
                            _prototype_header(markOopDesc::prototype()),
-                           _shared_class_path_index(-1),
-                           _java_mirror(NULL) {
+                           _shared_class_path_index(-1) {
   CDS_ONLY(_shared_class_flags = 0;)
   CDS_JAVA_HEAP_ONLY(_archived_mirror = 0;)
   _primary_supers[0] = this;