Fix: correctly destruct VIXL labels.

Bug: 27505766
Change-Id: I077465e3d308f4331e7a861902e05865f9d99835
diff --git a/compiler/optimizing/code_generator_mips64.h b/compiler/optimizing/code_generator_mips64.h
index 4e15cdd..9785a2e 100644
--- a/compiler/optimizing/code_generator_mips64.h
+++ b/compiler/optimizing/code_generator_mips64.h
@@ -271,7 +271,7 @@
 
   size_t GetFloatingPointSpillSlotSize() const OVERRIDE { return kMips64DoublewordSize; }
 
-  uintptr_t GetAddressOf(HBasicBlock* block) const OVERRIDE {
+  uintptr_t GetAddressOf(HBasicBlock* block) OVERRIDE {
     return assembler_.GetLabelLocation(GetLabelOf(block));
   }