Compatibility with MSYS2

[fauxpark]

MSYS2 has recently gotten a working Node. However, packages with prebuilt native code, such as bcrypt, do not work as the node-pre-gyp detects the OS as Windows (technically correct), but the library is incompatible with this build of Node. So, I've opened this issue to ask whether there's a preferred path for something like this to be solved.

Running node-pre-gyp rebuild gets it working, but it would be better if node-pre-gyp could detect whether it's running within MSYS2, and either try to pull an MSYS2-specific prebuilt library, or skip it entirely, and fall back to building from source. The former might be an issue as there are several variants of "native packages" in MSYS2, which are not compatible with each other.

More context here: msys2/MINGW-packages#15048