Use ATTRIBUTE_UNUSED more.

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

Change-Id: If247dce58b72056f6eea84968e7196f0b5bef4da
diff --git a/compiler/dex/pass_driver.h b/compiler/dex/pass_driver.h
index 8762b53..34a6f63 100644
--- a/compiler/dex/pass_driver.h
+++ b/compiler/dex/pass_driver.h
@@ -125,8 +125,7 @@
    * @brief Dispatch a patch.
    * Gives the ability to add logic when running the patch.
    */
-  virtual void DispatchPass(const Pass* pass) {
-    UNUSED(pass);
+  virtual void DispatchPass(const Pass* pass ATTRIBUTE_UNUSED) {
   }
 
   /** @brief List of passes: provides the order to execute the passes.