Update protobuf to r428, part 1.

third_party/protobuf/src/google/protobuf/stubs/atomicops_internals_macosx.h

Index: third_party/protobuf/src/google/protobuf/stubs/atomicops_internals_macosx.h
===================================================================
--- third_party/protobuf/src/google/protobuf/stubs/atomicops_internals_macosx.h	(revision 216642)
+++ third_party/protobuf/src/google/protobuf/stubs/atomicops_internals_macosx.h	(working copy)
@@ -136,7 +136,7 @@
   Atomic64 prev_value;
   do {
     if (OSAtomicCompareAndSwap64(old_value, new_value,
-                                 reinterpret_cast<volatile int64_t*>(ptr))) {
+                                 const_cast<Atomic64*>(ptr))) {
       return old_value;
     }
     prev_value = *ptr;
@@ -150,19 +150,18 @@
   do {
     old_value = *ptr;
   } while (!OSAtomicCompareAndSwap64(old_value, new_value,
-                                     reinterpret_cast<volatile int64_t*>(ptr)));
+                                     const_cast<Atomic64*>(ptr)));
   return old_value;
 }
 
 inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
                                           Atomic64 increment) {
-  return OSAtomicAdd64(increment, reinterpret_cast<volatile int64_t*>(ptr));
+  return OSAtomicAdd64(increment, const_cast<Atomic64*>(ptr));
 }
 
 inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
                                         Atomic64 increment) {
-  return OSAtomicAdd64Barrier(increment,
-                              reinterpret_cast<volatile int64_t*>(ptr));
+  return OSAtomicAdd64Barrier(increment, const_cast<Atomic64*>(ptr));
 }
 
 inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
@@ -170,8 +169,8 @@
                                        Atomic64 new_value) {
   Atomic64 prev_value;
   do {
-    if (OSAtomicCompareAndSwap64Barrier(
-        old_value, new_value, reinterpret_cast<volatile int64_t*>(ptr))) {
+    if (OSAtomicCompareAndSwap64Barrier(old_value, new_value,
+                                        const_cast<Atomic64*>(ptr))) {
       return old_value;
     }
     prev_value = *ptr;