msys: strip out cygwin paths from PATH
As mentioned earlier, I've been meaning to submit a patch for this for quite some time.
It's been around for some time as a gist:
This one's been tricky. Although I wrote it in August, just a couple of hours ago, I was still making non-trivial changes to it. Now, I'm pretty satisfied with it, enough to send it as a patch to msysgit.
