Various Windows / Cross Compile to Windows fixes

- Adds quick-cross-ncg flavour.
- Fix windows wchar with `_s` for mingw
- Lookup windres, dllwrap and objdump
- Fix type.

Reviewers: bgamari, hvr, Phyx, erikd, simonmar

Reviewed By: bgamari

Subscribers: rwbarton, thomie, erikd, carter

Differential Revision: https://phabricator.haskell.org/D4430