Fix ARM specific GYP variables

src/arm/constants-arm.h

 // Copyright 2011 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 26 matching lines @@
 // want to generate them on the simulator too so it makes snapshots that can
 // be used on real hardware.
 #if defined(__THUMB_INTERWORK__) || !defined(__arm__)
 # define USE_THUMB_INTERWORK 1
 #endif
 
 #if defined(__ARM_ARCH_7A__) || \
     defined(__ARM_ARCH_7R__) || \
     defined(__ARM_ARCH_7__)
 # define CAN_USE_ARMV7_INSTRUCTIONS 1
+#ifndef CAN_USE_VFP3_INSTRUCTIONS
 # define CAN_USE_VFP3_INSTRUCTIONS
 #endif
+#endif
 
 #if defined(__ARM_ARCH_6__)   ||   \
     defined(__ARM_ARCH_6J__)  ||  \
     defined(__ARM_ARCH_6K__)  ||  \
     defined(__ARM_ARCH_6Z__)  ||  \
     defined(__ARM_ARCH_6ZK__) || \
     defined(__ARM_ARCH_6T2__) || \
     defined(CAN_USE_ARMV7_INSTRUCTIONS)
 # define CAN_USE_ARMV6_INSTRUCTIONS 1
 #endif
@@ skipping 722 matching lines @@
   static int Number(const char* name, bool* is_double);
 
  private:
   static const char* names_[kNumVFPRegisters];
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_CONSTANTS_ARM_H_