Use ATTRIBUTE_UNUSED more.

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

Change-Id: If247dce58b72056f6eea84968e7196f0b5bef4da
diff --git a/compiler/dex/quick/gen_common.cc b/compiler/dex/quick/gen_common.cc
index 2a1d644..2b60a51 100644
--- a/compiler/dex/quick/gen_common.cc
+++ b/compiler/dex/quick/gen_common.cc
@@ -2102,15 +2102,15 @@
 }
 
 /* Call out to helper assembly routine that will null check obj and then lock it. */
-void Mir2Lir::GenMonitorEnter(int opt_flags, RegLocation rl_src) {
-  UNUSED(opt_flags);  // TODO: avoid null check with specialized non-null helper.
+void Mir2Lir::GenMonitorEnter(int opt_flags ATTRIBUTE_UNUSED, RegLocation rl_src) {
+  // TODO: avoid null check with specialized non-null helper.
   FlushAllRegs();
   CallRuntimeHelperRegLocation(kQuickLockObject, rl_src, true);
 }
 
 /* Call out to helper assembly routine that will null check obj and then unlock it. */
-void Mir2Lir::GenMonitorExit(int opt_flags, RegLocation rl_src) {
-  UNUSED(opt_flags);  // TODO: avoid null check with specialized non-null helper.
+void Mir2Lir::GenMonitorExit(int opt_flags ATTRIBUTE_UNUSED, RegLocation rl_src) {
+  // TODO: avoid null check with specialized non-null helper.
   FlushAllRegs();
   CallRuntimeHelperRegLocation(kQuickUnlockObject, rl_src, true);
 }