MIPS32: Ensure preservation of RA in leaf methods if it's clobbered

Test: booted MIPS32 in QEMU
Test: test-art-host-gtest
Test: test-art-target-gtest-codegen_test in QEMU
Test: test-art-target-run-test-optimizing on CI20

Change-Id: Ia3da5902d967cd7af313f03ebf414320b0063619
diff --git a/compiler/optimizing/code_generator_mips.h b/compiler/optimizing/code_generator_mips.h
index 46810d6..68e62b3 100644
--- a/compiler/optimizing/code_generator_mips.h
+++ b/compiler/optimizing/code_generator_mips.h
@@ -274,6 +274,7 @@
   virtual ~CodeGeneratorMIPS() {}
 
   void ComputeSpillMask() OVERRIDE;
+  bool HasAllocatedCalleeSaveRegisters() const OVERRIDE;
   void GenerateFrameEntry() OVERRIDE;
   void GenerateFrameExit() OVERRIDE;