Added MIPS instrumentation support.

Traceview works on MIPS, but deoptimization is untested.

Change-Id: I8b8afc8003f02965be8b3e0beca57416142c5725
diff --git a/src/oat/runtime/mips/context_mips.h b/src/oat/runtime/mips/context_mips.h
index d4944a6..76a5957 100644
--- a/src/oat/runtime/mips/context_mips.h
+++ b/src/oat/runtime/mips/context_mips.h
@@ -44,7 +44,7 @@
 
   virtual uintptr_t GetGPR(uint32_t reg) {
     CHECK_LT(reg, kNumberOfCoreRegisters);
-    return gprs_[reg];
+    return *gprs_[reg];
   }
 
   virtual void SetGPR(uint32_t reg, uintptr_t value);