Add support for building v8 on mips and mips64 using GN.

build/build_config.h

 // Copyright (c) 2012 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) /
 //    OS_NACL (NACL_SFI or NACL_NONSFI) / OS_NACL_SFI / OS_NACL_NONSFI
 //    OS_CHROMEOS is set by the build system
 //  Compiler:
@@ skipping 140 matching lines @@
 #define ARCH_CPU_MIPS_FAMILY 1
 #define ARCH_CPU_MIPS64EL 1
 #define ARCH_CPU_64_BITS 1
 #define ARCH_CPU_LITTLE_ENDIAN 1
 #else
 #define ARCH_CPU_MIPS_FAMILY 1
 #define ARCH_CPU_MIPSEL 1
 #define ARCH_CPU_32_BITS 1
 #define ARCH_CPU_LITTLE_ENDIAN 1
 #endif
+#elif defined(__MIPSEB__)
+#if defined(__LP64__)
+#define ARCH_CPU_MIPS_FAMILY 1
+#define ARCH_CPU_MIPS64 1
+#define ARCH_CPU_64_BITS 1
+#define ARCH_CPU_BIG_ENDIAN 1
+#else
+#define ARCH_CPU_MIPS_FAMILY 1
+#define ARCH_CPU_MIPS 1
+#define ARCH_CPU_32_BITS 1
+#define ARCH_CPU_BIG_ENDIAN 1
+#endif
 #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 || __WCHAR_MAX__ == 0xffffffff)
@@ skipping 13 matching lines @@
 #if defined(OS_ANDROID)
 // The compiler thinks std::string::const_iterator and "const char*" are
 // equivalent types.
 #define STD_STRING_ITERATOR_IS_CHAR_POINTER
 // The compiler thinks base::string16::const_iterator and "char16*" are
 // equivalent types.
 #define BASE_STRING16_ITERATOR_IS_CHAR16_POINTER
 #endif
 
 #endif  // BUILD_BUILD_CONFIG_H_