Make NoReloadScope thread safe

runtime/vm/atomic_android.h

Index: runtime/vm/atomic_android.h
diff --git a/runtime/vm/atomic_android.h b/runtime/vm/atomic_android.h
index 689173a2ac65783aeddafc5828e455bf8c5644c5..aa2b623c92cddd7a2fe6f960419561472fdd5572 100644
--- a/runtime/vm/atomic_android.h
+++ b/runtime/vm/atomic_android.h
@@ -21,6 +21,11 @@ inline uintptr_t AtomicOperations::FetchAndIncrement(uintptr_t* p) {
 }
 
 
+inline intptr_t AtomicOperations::FetchAndIncrement(intptr_t* p) {
+  return __sync_fetch_and_add(p, 1);
+}
+
+
 inline void AtomicOperations::IncrementBy(intptr_t* p, intptr_t value) {
   __sync_fetch_and_add(p, value);
 }
@@ -36,6 +41,11 @@ inline uintptr_t AtomicOperations::FetchAndDecrement(uintptr_t* p) {
 }
 
 
+inline intptr_t AtomicOperations::FetchAndDecrement(intptr_t* p) {
+  return __sync_fetch_and_sub(p, 1);
+}
+
+
 inline void AtomicOperations::DecrementBy(intptr_t* p, intptr_t value) {
   __sync_fetch_and_sub(p, value);
 }