Changes to build 'winhttp.c'

* src/libgit2/transports/winhttp.c (winhttp_stream_connect): Changes
  to fix compiler warning: change 'wchar_t *types[]' to 'const
  WCHAR *types[]'

* misc/winhttp-build-with-mingw-w64.patch: Update

Signed-off-by: Stefan Widgren <stefan.widgren@gmail.com>