Make the android arm sigcontext structure match glibc.

src/platform-linux.cc

 // 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 593 matching lines @@
     mcontext_t& mcontext = ucontext->uc_mcontext;
 #if V8_HOST_ARCH_IA32
     sample.pc = mcontext.gregs[REG_EIP];
     sample.sp = mcontext.gregs[REG_ESP];
     sample.fp = mcontext.gregs[REG_EBP];
 #elif V8_HOST_ARCH_X64
     sample.pc = mcontext.gregs[REG_RIP];
     sample.sp = mcontext.gregs[REG_RSP];
     sample.fp = mcontext.gregs[REG_RBP];
 #elif V8_HOST_ARCH_ARM
+// An undefined macro evaluates to 0, so this applies to Android's Bionic also.
+#if (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
     sample.pc = mcontext.gregs[R15];
     sample.sp = mcontext.gregs[R13];
     sample.fp = mcontext.gregs[R11];
+#else
+    sample.pc = mcontext.arm_pc;
+    sample.sp = mcontext.arm_sp;
+    sample.fp = mcontext.arm_fp;
+#endif
 #endif
   }
 
   // We always sample the VM state.
   sample.state = Logger::state();
 
   active_sampler_->Tick(&sample);
 }
 
 
@@ skipping 56 matching lines @@
   }
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
   active_ = false;
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal