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/include/gui/Sensor.h b/include/gui/Sensor.h
index 28a08e2..59b4d4d 100644
--- a/include/gui/Sensor.h
+++ b/include/gui/Sensor.h
@@ -98,7 +98,7 @@
     String8 mStringType;
     String8 mRequiredPermission;
     int32_t mMaxDelay;
-    int32_t mFlags;
+    uint32_t mFlags;
     static void flattenString8(void*& buffer, size_t& size, const String8& string8);
     static bool unflattenString8(void const*& buffer, size_t& size, String8& outputString8);
 };