Allow mixing of thread offsets between 32 and 64bit architectures.

Begin a more full implementation x86-64 REX prefixes.
Doesn't implement 64bit thread offset support for the JNI compiler.

Change-Id: If9af2f08a1833c21ddb4b4077f9b03add1a05147
diff --git a/compiler/dex/quick/mips/utility_mips.cc b/compiler/dex/quick/mips/utility_mips.cc
index 4f31341..c959510 100644
--- a/compiler/dex/quick/mips/utility_mips.cc
+++ b/compiler/dex/quick/mips/utility_mips.cc
@@ -642,7 +642,7 @@
   return StoreBaseDispBody(r_base, displacement, r_src.GetLow(), r_src.GetHigh(), kLong);
 }
 
-LIR* MipsMir2Lir::OpThreadMem(OpKind op, ThreadOffset thread_offset) {
+LIR* MipsMir2Lir::OpThreadMem(OpKind op, ThreadOffset<4> thread_offset) {
   LOG(FATAL) << "Unexpected use of OpThreadMem for MIPS";
   return NULL;
 }