Add support for MSYS Makefiles in acprep
Add support for MSYS Makefiles in acprep

Useful for building in a MINGW32/64 console on Windows.

afh/ledger,afh/ledger,ledger/ledger,ledger/ledger,ledger/ledger,afh/ledger,ledger/ledger,ledger/ledger,afh/ledger,afh/ledger