frameworks/base: Fix build in ISO C++11 mode

Fix various incompatibilities with ISO C++11:
- Assumption that char16_t is defined to uint16_t
- constexpr usage
- macro constructs that could be interpreted as string literals
- enum typesafety

Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>

Conflicts:
	cmds/stagefright/SineSource.h
	core/jni/android/graphics/TextLayoutCache.cpp
	core/jni/android_util_Binder.cpp
	core/jni/android_view_KeyCharacterMap.cpp
	libs/gui/SurfaceTexture.cpp
	media/libstagefright/OMXCodec.cpp
	services/audioflinger/AudioResampler.h

Change-Id: I185b97f07e89bed93b92546bc0fdf895bd0cc92d