Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

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

 // Protocol Buffers - Google's data interchange format
 // Copyright 2012 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
@@ skipping 29 matching lines @@
 //   or with gcc, run: "echo | gcc -E -dM -"
 #if defined(_M_X64) || defined(__x86_64__)
 #define GOOGLE_PROTOBUF_ARCH_X64 1
 #define GOOGLE_PROTOBUF_ARCH_64_BIT 1
 #elif defined(_M_IX86) || defined(__i386__)
 #define GOOGLE_PROTOBUF_ARCH_IA32 1
 #define GOOGLE_PROTOBUF_ARCH_32_BIT 1
 #elif defined(__QNX__)
 #define GOOGLE_PROTOBUF_ARCH_ARM_QNX 1
 #define GOOGLE_PROTOBUF_ARCH_32_BIT 1
-#elif defined(_M_ARM) || defined(__ARMEL__)
+#elif defined(__ARMEL__)
 #define GOOGLE_PROTOBUF_ARCH_ARM 1
 #define GOOGLE_PROTOBUF_ARCH_32_BIT 1
 #elif defined(__aarch64__)
 #define GOOGLE_PROTOBUF_ARCH_AARCH64 1
 #define GOOGLE_PROTOBUF_ARCH_64_BIT 1
 #elif defined(__MIPSEL__)
 #if defined(__LP64__)
 #define GOOGLE_PROTOBUF_ARCH_MIPS64 1
 #define GOOGLE_PROTOBUF_ARCH_64_BIT 1
 #else
@@ skipping 46 matching lines @@
 #elif defined(sun)
 #define GOOGLE_PROTOBUF_OS_SOLARIS
 #elif defined(_AIX)
 #define GOOGLE_PROTOBUF_OS_AIX
 #elif defined(__ANDROID__)
 #define GOOGLE_PROTOBUF_OS_ANDROID
 #endif
 
 #undef GOOGLE_PROTOBUF_PLATFORM_ERROR
 
-#if defined(GOOGLE_PROTOBUF_OS_ANDROID) || defined(GOOGLE_PROTOBUF_OS_IPHONE) || defined(__OpenBSD__)
+#if defined(GOOGLE_PROTOBUF_OS_ANDROID) || defined(GOOGLE_PROTOBUF_OS_IPHONE)
 // Android ndk does not support the __thread keyword very well yet. Here
 // we use pthread_key_create()/pthread_getspecific()/... methods for
 // TLS support on android.
-// iOS and OpenBSD also do not support the __thread keyword.
+// iOS also does not support the __thread keyword.
 #define GOOGLE_PROTOBUF_NO_THREADLOCAL
 #endif
 
 #endif  // GOOGLE_PROTOBUF_PLATFORM_MACROS_H_