Quick: Clean up Mir2Lir codegen.

Clean up WrapPointer()/UnwrapPointer() and OpPcRelLoad().

Change-Id: I1a91f01e1e779599c77f3f6efcac2a6ad34629cf
diff --git a/compiler/dex/quick/mips/int_mips.cc b/compiler/dex/quick/mips/int_mips.cc
index 8c9acf6..8093c97 100644
--- a/compiler/dex/quick/mips/int_mips.cc
+++ b/compiler/dex/quick/mips/int_mips.cc
@@ -348,7 +348,7 @@
   return true;
 }
 
-LIR* MipsMir2Lir::OpPcRelLoad(RegStorage reg, LIR* target) {
+void MipsMir2Lir::OpPcRelLoad(RegStorage reg, LIR* target) {
   UNUSED(reg, target);
   LOG(FATAL) << "Unexpected use of OpPcRelLoad for Mips";
   UNREACHABLE();