Add atomic operations for ARM.

build/build_config.h

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file adds defines about the platform we're currently building on.
 //  Operating System:
 //    OS_WIN / OS_MACOSX / OS_LINUX / OS_POSIX (MACOSX or LINUX)
 //  Compiler:
 //    COMPILER_MSVC / COMPILER_GCC
 //  Processor:
@@ skipping 25 matching lines @@
 #define COMPILER_GCC 1
 #elif defined(_MSC_VER)
 #define COMPILER_MSVC 1
 #else
 #error Please add support for your compiler in build/build_config.h
 #endif
 
 // Processor architecture detection.  For more info on what's defined, see:
 //   http://msdn.microsoft.com/en-us/library/b0084kay.aspx
 //   http://www.agner.org/optimize/calling_conventions.pdf
+//   or with gcc, run: "echo | gcc -E -dM -"
 #if defined(_M_X64) || defined(__x86_64__)
 #define ARCH_CPU_X86_FAMILY 1
 #define ARCH_CPU_X86_64 1
 #define ARCH_CPU_64_BITS 1
 #elif defined(_M_IX86) || defined(__i386__)
 #define ARCH_CPU_X86_FAMILY 1
 #define ARCH_CPU_X86 1
 #define ARCH_CPU_32_BITS 1
+#elif defined(__ARMEL__)
+#define ARCH_CPU_ARM_FAMILY 1
+#define ARCH_CPU_ARMEL 1
+#define ARCH_CPU_32_BITS 1
 #else
 #error Please add support for your architecture in build/build_config.h
 #endif
 
 // Type detection for wchar_t.
 #if defined(OS_WIN)
 #define WCHAR_T_IS_UTF16
 #elif defined(OS_POSIX) && defined(COMPILER_GCC) && \
-    defined(__WCHAR_MAX__) && __WCHAR_MAX__ == 0x7fffffff
+    defined(__WCHAR_MAX__) && \
+    (__WCHAR_MAX__ == 0x7fffffff || __WCHAR_MAX__ == 0xffffffff)
 #define WCHAR_T_IS_UTF32
 #else
 #error Please add support for your compiler in build/build_config.h
 #endif
 
 #endif  // BUILD_BUILD_CONFIG_H_