Use the pnacl-clang toolchain for (P)NaCL builds

src/base/build_config.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BASE_BUILD_CONFIG_H_
 #define V8_BASE_BUILD_CONFIG_H_
 
 #include "include/v8config.h"
 
 // Processor architecture detection.  For more info on what's defined, see:
@@ skipping 11 matching lines @@
 #define V8_HOST_ARCH_IA32 1
 #define V8_HOST_ARCH_32_BIT 1
 #else
 #define V8_HOST_ARCH_X64 1
 #if defined(__x86_64__) && __SIZEOF_POINTER__ == 4  // Check for x32.
 #define V8_HOST_ARCH_32_BIT 1
 #else
 #define V8_HOST_ARCH_64_BIT 1
 #endif
 #endif  // __native_client__
+#elif defined(__pnacl__)
+// PNaCl is also ILP-32.
+#define V8_HOST_ARCH_IA32 1
+#define V8_HOST_ARCH_32_BIT 1
 #elif defined(_M_IX86) || defined(__i386__)
 #define V8_HOST_ARCH_IA32 1
 #define V8_HOST_ARCH_32_BIT 1
 #elif defined(__AARCH64EL__)
 #define V8_HOST_ARCH_ARM64 1
 #define V8_HOST_ARCH_64_BIT 1
 #elif defined(__ARMEL__)
 #define V8_HOST_ARCH_ARM 1
 #define V8_HOST_ARCH_32_BIT 1
 #elif defined(__mips64)
@@ skipping 110 matching lines @@
 #define V8_TARGET_LITTLE_ENDIAN 1
 #else
 #error Unknown target architecture endianness
 #endif
 
 // Number of bits to represent the page size for paged spaces. The value of 20
 // gives 1Mb bytes per page.
 const int kPageSizeBits = 20;
 
 #endif  // V8_BASE_BUILD_CONFIG_H_