This can also be used instead of the WindowsSupport.h ConvertUTF8ToUTF16
helpers, but that will require massaging some character types. The
Windows support routines want wchar_t output, but wchar_t is often 32
bits on non-Windows OSs.
llvm-svn: 227122
This is to support parsing UTF16 response files in LLVM/lib/Option for
lld and clang.
Reviewers: hans
Differential Revision: http://llvm-reviews.chandlerc.com/D1138
llvm-svn: 186426