Move setlocale(3) and the wchar stubs over to .cpp.

Also separate out the C++ files so we can use -Werror on them. I'd
rather wait for LOCAL_CPPFLAGS to be in AOSP, but this also lets us
see which files still need to be sorted into one bucket or the other.

Change-Id: I6acc1f7c043935c70a3b089f705d218b9aaaba0a
4 files changed