Rosalloc thread local allocation path without a cas.

Speedup on N4:
MemAllocTest 3044 -> 2396 (~21% reduction)
BinaryTrees  4101 -> 2929 (~26% reduction)

Bug: 9986565
Change-Id: Ia1d1a37b9e001f903c3c056e8ec68fc8c623a78b
diff --git a/runtime/gc/space/bump_pointer_space.cc b/runtime/gc/space/bump_pointer_space.cc
index fbfc449..1303d77 100644
--- a/runtime/gc/space/bump_pointer_space.cc
+++ b/runtime/gc/space/bump_pointer_space.cc
@@ -93,12 +93,13 @@
   return reinterpret_cast<mirror::Object*>(RoundUp(position, kAlignment));
 }
 
-void BumpPointerSpace::RevokeThreadLocalBuffers(Thread* thread) {
+size_t BumpPointerSpace::RevokeThreadLocalBuffers(Thread* thread) {
   MutexLock mu(Thread::Current(), block_lock_);
   RevokeThreadLocalBuffersLocked(thread);
+  return 0U;
 }
 
-void BumpPointerSpace::RevokeAllThreadLocalBuffers() {
+size_t BumpPointerSpace::RevokeAllThreadLocalBuffers() {
   Thread* self = Thread::Current();
   MutexLock mu(self, *Locks::runtime_shutdown_lock_);
   MutexLock mu2(self, *Locks::thread_list_lock_);
@@ -107,6 +108,7 @@
   for (Thread* thread : thread_list) {
     RevokeThreadLocalBuffers(thread);
   }
+  return 0U;
 }
 
 void BumpPointerSpace::AssertThreadLocalBuffersAreRevoked(Thread* thread) {