Enable clang for libui/libgui/surfaceflinger

Enables clang and C++11 for libui/libgui/surfaceflinger, and
eliminates all compile-time warnings.

Change-Id: Ie237fdb5ae44f2bfcddaa884f9c65ec3f08ae50f
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 77fc347..43a69df 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -607,7 +607,7 @@
     return NO_ERROR;
 }
 
-status_t SurfaceFlinger::getDisplayStats(const sp<IBinder>& display,
+status_t SurfaceFlinger::getDisplayStats(const sp<IBinder>& /* display */,
         DisplayStatInfo* stats) {
     if (stats == NULL) {
         return BAD_VALUE;