8208061: runtime/LoadClass/TestResize.java fails with "Load factor too high" when running in CDS mode

Allow resizing for all system dictionaries except for the shared dictionary at runtime.

Reviewed-by: iklam, gziemski

src/hotspot/share/classfile/systemDictionary.cpp

@@ -1160,10 +1160,12 @@ InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
 #if INCLUDE_CDS
 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
                                              int number_of_entries) {
+  assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
          "bad shared dictionary size.");
   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
-                                      _shared_dictionary_size, t, number_of_entries);
+                                      _shared_dictionary_size, t, number_of_entries,
+                                      false /* explicitly set _resizable to false */);
 }