Introduce processor detection in globals.h, instead of from the build system.

src/codegen.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 58 matching lines @@
 //   CodeForFunctionPosition
 //   CodeForReturnPosition
 //   CodeForStatementPosition
 //   CodeForSourcePosition
 
 
 // Mode to overwrite BinaryExpression values.
 enum OverwriteMode { NO_OVERWRITE, OVERWRITE_LEFT, OVERWRITE_RIGHT };
 
 
-#ifdef V8_ARCH_ARM
+#if V8_TARGET_ARCH_IA32
+#include "ia32/codegen-ia32.h"
+#elif V8_TARGET_ARCH_X64
+#include "x64/codegen-x64.h"
+#elif V8_TARGET_ARCH_ARM
 #include "arm/codegen-arm.h"
 #endif
 
-#ifdef V8_ARCH_X64
-#include "x64/codegen-x64.h"
-#endif
-
-#ifdef V8_ARCH_IA32
-#include "ia32/codegen-ia32.h"
-#endif
-
 namespace v8 { namespace internal {
 
 
 // Use lazy compilation; defaults to true.
 // NOTE: Do not remove non-lazy compilation until we can properly
 //       install extensions with lazy compilation enabled. At the
 //       moment, this doesn't work for the extensions in Google3,
 //       and we can only run the tests with --nolazy.
 
 
@@ skipping 215 matching lines @@
     PrintF("ArgumentsAccessStub (type %d)\n", type_);
   }
 #endif
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CODEGEN_H_