Move the Parallel GC specific task creation functions out of Threads

This code should be moved into gc/parallel:
-#if INCLUDE_PARALLELGC
-// Used by ParallelScavenge
-void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
- ALL_JAVA_THREADS(p) {
- q->enqueue(new ThreadRootsTask(p));
- }
- q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
-}
-
-// Used by Parallel Old
-void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
- ALL_JAVA_THREADS(p) {
- q->enqueue(new ThreadRootsMarkingTask(p));
- }
- q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
-}
-#endif // INCLUDE_PARALLELGC