Merge pull request #30 from edmonds/branches/fix_generic_atomicops_memory_models

generic atomicops: promote Acquire_Store() and Release_Load() to use SEQ_CST fence

src/google/protobuf/stubs/atomicops_internals_generic_gcc.h

@@ -83,7 +83,7 @@ inline void MemoryBarrier() {
 }
 
 inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
-  __atomic_store_n(ptr, value, __ATOMIC_ACQUIRE);
+  __atomic_store_n(ptr, value, __ATOMIC_SEQ_CST);
 }
 
 inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
@@ -99,7 +99,7 @@ inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
 }
 
 inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
-  return __atomic_load_n(ptr, __ATOMIC_RELEASE);
+  return __atomic_load_n(ptr, __ATOMIC_SEQ_CST);
 }
 
 #ifdef __LP64__