OpenRTC2 requires safecrt exports to be present in msvcrt and others (nt6 compatibility)

OpenRCT2 can be made to work on ReactOS, as proven here: https://www.reddit.com/r/reactos/comments/69to9s/openrct2_works_fine_on_reactos_044/

There are only a handful of required exports from _WIN32_WINNT >= 0x0600:

• GetLocaleInfoEx
• wcscpy_s
• SHGetPathFromIDListEx
• RegDeleteTree{A,W}

Those should make it possible to launch MinGW builds of OpenRCT2 on ReactOS.

Our own, first-party builds are done with AppVeyor using (as of writing) MSVC 2017 15.3, with subsystem set to something else than 5.1, which exhibits the issue where trying to launch the .exe results in ERROR_BAD_EXE_FORMAT message. I'm testing this with my own MinGW-w64 builds.

Our first-party builds can be obtained from http://openrct2.org/downloads or via following one of recent AppVeyor builds from commits on GitHub.