This work was done (almost) entirely without any MSFT involvement. Contributions were done by a bunch of guys affectionally called "the port team" whom you wouldn't want to meet in a (technical) dark alleyway ;)
@janhenke, @josteink, @ajensenwaud, @xied75, @kangaroo, @ghuntley, @qbit & @richlander (MSFT)
https://github.com/dotnet/coreclr/issues/455
edit: Special shoutout to interoute.com and Paul Kelly whom comped the infrastructure needed for the team to collaborate on/test with FreeBSD, NetBSD and OpenBSD.
edit: Extra special shoutout to @kangaroo who was the first successfully merged pull request after MSFT open-sourced everything. His commits added support for .NET on OSX. He was awarded a custom, personalized/engraved scotch glass at the recent .NETFringe open-source .NET conference in portland a couple weeks ago.