ARM: Support hardfloat in SCons build and make it a build time setting

src/platform.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 276 matching lines @@
   // of the CPU and the OS.  The bits in the answer correspond to the bit
   // positions indicated by the members of the CpuFeature enum from globals.h
   static uint64_t CpuFeaturesImpliedByPlatform();
 
   // Returns the double constant NAN
   static double nan_value();
 
   // Support runtime detection of VFP3 on ARM CPUs.
   static bool ArmCpuHasFeature(CpuFeature feature);
 
+  // Support runtime detection of whether the hard float option of the
+  // EABI is used.
+  static bool ArmUsingHardFloat();
+
   // Support runtime detection of FPU on MIPS CPUs.
   static bool MipsCpuHasFeature(CpuFeature feature);
 
   // Returns the activation frame alignment constraint or zero if
   // the platform doesn't care. Guaranteed to be a power of two.
   static int ActivationFrameAlignment();
 
   static void ReleaseStore(volatile AtomicWord* ptr, AtomicWord value);
 
 #if defined(V8_TARGET_ARCH_IA32)
@@ skipping 347 matching lines @@
   int samples_taken_;  // Counts stack samples taken.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_