Enable clang for libui/libgui/surfaceflinger

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

Change-Id: Ie237fdb5ae44f2bfcddaa884f9c65ec3f08ae50f
(cherry picked from commit f10c46ef855b6410b20ebd8b1351d4d78d8eca8e)
diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index 9a2411a..13d44f3 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -517,6 +517,6 @@
         tr[0][2], tr[1][2], tr[2][2]);
 
     String8 surfaceDump;
-    mDisplaySurface->dump(surfaceDump);
+    mDisplaySurface->dumpAsString(surfaceDump);
     result.append(surfaceDump);
 }