Use ATTRIBUTE_UNUSED more.

Use it in lieu of UNUSED(), which had some incorrect uses.

Change-Id: If247dce58b72056f6eea84968e7196f0b5bef4da
diff --git a/compiler/dex/quick/mir_to_lir.h b/compiler/dex/quick/mir_to_lir.h
index 4e3aab2..a0db1e8 100644
--- a/compiler/dex/quick/mir_to_lir.h
+++ b/compiler/dex/quick/mir_to_lir.h
@@ -1463,8 +1463,7 @@
     virtual bool InexpensiveConstantFloat(int32_t value) = 0;
     virtual bool InexpensiveConstantLong(int64_t value) = 0;
     virtual bool InexpensiveConstantDouble(int64_t value) = 0;
-    virtual bool InexpensiveConstantInt(int32_t value, Instruction::Code opcode) {
-      UNUSED(opcode);
+    virtual bool InexpensiveConstantInt(int32_t value, Instruction::Code opcode ATTRIBUTE_UNUSED) {
       return InexpensiveConstantInt(value);
     }