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/DisplayHardware/VirtualDisplaySurface.cpp b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
index c3d45ee..e0f32e9 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
@@ -254,7 +254,7 @@
     resetPerFrameState();
 }
 
-void VirtualDisplaySurface::dump(String8& /* result */) const {
+void VirtualDisplaySurface::dumpAsString(String8& /* result */) const {
 }
 
 void VirtualDisplaySurface::resizeBuffers(const uint32_t w, const uint32_t h) {