Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

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

Index: third_party/protobuf/src/google/protobuf/stubs/atomicops.h
diff --git a/third_party/protobuf/src/google/protobuf/stubs/atomicops.h b/third_party/protobuf/src/google/protobuf/stubs/atomicops.h
index c25492f3200536a7e975ccce40fd36e4957ae66f..9b3d1e6b57d25ec82ceb25ad8a1baef66ebd5346 100644
--- a/third_party/protobuf/src/google/protobuf/stubs/atomicops.h
+++ b/third_party/protobuf/src/google/protobuf/stubs/atomicops.h
@@ -123,8 +123,8 @@ Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
 // ensure that no later memory access can be reordered ahead of the operation.
 // "Release" operations ensure that no previous memory access can be reordered
 // after the operation.  "Barrier" operations have both "Acquire" and "Release"
-// semantics.   A MemoryBarrierInternal() has "Barrier" semantics, but does no
-// memory access.
+// semantics.   A MemoryBarrier() has "Barrier" semantics, but does no memory
+// access.
 Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
                                 Atomic32 old_value,
                                 Atomic32 new_value);
@@ -132,10 +132,10 @@ Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
                                 Atomic32 old_value,
                                 Atomic32 new_value);
 
-// This function was renamed from MemoryBarrier to MemoryBarrierInternal
-// because MemoryBarrier is a define in Windows ARM builds and we do not
-// undefine it because we call it from this function.
-void MemoryBarrierInternal();
+#if defined(__MINGW32__) && defined(MemoryBarrier)
+#undef MemoryBarrier
+#endif
+void MemoryBarrier();
 void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value);
 void Acquire_Store(volatile Atomic32* ptr, Atomic32 value);
 void Release_Store(volatile Atomic32* ptr, Atomic32 value);
@@ -180,7 +180,7 @@ Atomic64 Release_Load(volatile const Atomic64* ptr);
 #include <google/protobuf/stubs/atomicops_internals_tsan.h>
 // MSVC.
 #elif defined(_MSC_VER)
-#if defined(GOOGLE_PROTOBUF_ARCH_IA32) || defined(GOOGLE_PROTOBUF_ARCH_X64) || defined(GOOGLE_PROTOBUF_ARCH_ARM)
+#if defined(GOOGLE_PROTOBUF_ARCH_IA32) || defined(GOOGLE_PROTOBUF_ARCH_X64)
 #include <google/protobuf/stubs/atomicops_internals_x86_msvc.h>
 #else
 #error GOOGLE_PROTOBUF_ATOMICOPS_ERROR
@@ -196,22 +196,14 @@ Atomic64 Release_Load(volatile const Atomic64* ptr);
 
 // Apple.
 #elif defined(GOOGLE_PROTOBUF_OS_APPLE)
-#if __has_feature(cxx_atomic) || _GNUC_VER >= 407
-#include <google/protobuf/stubs/atomicops_internals_generic_c11_atomic.h>
-#else  // __has_feature(cxx_atomic) || _GNUC_VER >= 407
 #include <google/protobuf/stubs/atomicops_internals_macosx.h>
-#endif  // __has_feature(cxx_atomic) || _GNUC_VER >= 407
 
 // GCC.
 #elif defined(__GNUC__)
 #if defined(GOOGLE_PROTOBUF_ARCH_IA32) || defined(GOOGLE_PROTOBUF_ARCH_X64)
 #include <google/protobuf/stubs/atomicops_internals_x86_gcc.h>
 #elif defined(GOOGLE_PROTOBUF_ARCH_ARM) && defined(__linux__)
-#if (((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4))
-#include <google/protobuf/stubs/atomicops_internals_generic_gcc.h>
-#else
 #include <google/protobuf/stubs/atomicops_internals_arm_gcc.h>
-#endif
 #elif defined(GOOGLE_PROTOBUF_ARCH_AARCH64)
 #include <google/protobuf/stubs/atomicops_internals_arm64_gcc.h>
 #elif defined(GOOGLE_PROTOBUF_ARCH_ARM_QNX)
@@ -221,7 +213,7 @@ Atomic64 Release_Load(volatile const Atomic64* ptr);
 #elif defined(GOOGLE_PROTOBUF_ARCH_POWER)
 #include <google/protobuf/stubs/atomicops_internals_power.h>
 #elif defined(__native_client__)
-#include <google/protobuf/stubs/atomicops_internals_generic_c11_atomic.h>
+#include <google/protobuf/stubs/atomicops_internals_pnacl.h>
 #elif defined(GOOGLE_PROTOBUF_ARCH_PPC)
 #include <google/protobuf/stubs/atomicops_internals_ppc_gcc.h>
 #elif (((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4))