Remove ALLOW_UNUSED.

Turns out Chromium won't be applying this to COMPILE_ASSERT. We don't
need it at all then.

R=thakis@chromium.org
TBR=thakis@chromium.org

Review URL: https://webrtc-codereview.appspot.com/13469005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6055 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/system_wrappers/interface/compile_assert.h b/webrtc/system_wrappers/interface/compile_assert.h
index 46e40ac..a075184 100644
--- a/webrtc/system_wrappers/interface/compile_assert.h
+++ b/webrtc/system_wrappers/interface/compile_assert.h
@@ -41,7 +41,7 @@
 };
 
 #define COMPILE_ASSERT(expr, msg) \
-  typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1] ALLOW_UNUSED
+  typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
 
 #endif  //  __cplusplus >= 201103L
 #endif  //  !defined(COMPILE_ASSERT)