8241444: Metaspace::_class_vsm not initialized if compressed class pointers are disabled

Summary: Initialize _class_vsm to NULL by default
Reviewed-by: phh
Contributed-by: thomas.stuefe@gmail.com

src/share/vm/memory/metaspace.cpp

@@ -3390,6 +3390,8 @@ void Metaspace::initialize(Mutex* lock, MetaspaceType type) {
   if (using_class_space()) {
     // Allocate SpaceManager for classes.
     _class_vsm = new SpaceManager(ClassType, lock);
+  } else {
+    _class_vsm = NULL;
   }
 
   MutexLockerEx cl(SpaceManager::expand_lock(), Mutex::_no_safepoint_check_flag);