Scope ANGLE_UNUSED_VARIABLE.

Renames the macro to be more ANGLE-ey.

Refactoring only.

Bug: angleproject:1671
Change-Id: I8f2dd227c7e2025886ec66e85efa877ea261d0ad
Reviewed-on: https://chromium-review.googlesource.com/1036209
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/Context.cpp b/src/libANGLE/Context.cpp
index 132271c..4de0868 100644
--- a/src/libANGLE/Context.cpp
+++ b/src/libANGLE/Context.cpp
@@ -297,8 +297,8 @@
       mZeroFilledBuffer(1000u)
 {
     // Needed to solve a Clang warning of unused variables.
-    UNUSED_VARIABLE(mSavedArgsType);
-    UNUSED_VARIABLE(mParamsBuffer);
+    ANGLE_UNUSED_VARIABLE(mSavedArgsType);
+    ANGLE_UNUSED_VARIABLE(mParamsBuffer);
 
     mImplementation->setMemoryProgramCache(memoryProgramCache);