[freetds] Add new port

[maharmstone]

Adds port for FreeTDS (https://www.freetds.org/), the free implementation of the Tabular Data Stream protocol that Microsoft SQL Server uses to communicate.

[msftclas]

All CLA requirements met.

[NancyLi1013]

Hi @maharmstone, thanks for the new port. Here are the test results from the current CI system:

x64-windows	test	notes
freetds	Pass	New Port

x64-windows-static	test	notes
freetds	Pass	New Port

x64-osx	test	notes
freetds	Fail	New Port

arm64-windows	test	notes
freetds	Fail	New Port

x86-windows	test	notes
freetds	Pass	New Port

x64-linux	test	notes
freetds	Fail	New Port

x64-uwp	test	notes
freetds	Fail	New Port

arm-uwp	test	notes
freetds	Fail	New Port

failureLogs.zip

[Rastaban]

@maharmstone this port is looking good to me so far and is passing the windows and windows-static builds. Are you interested in investigating the failures on other triplets? If you don't have time then I will merge this as is and the other triplets can be addressed in a separate PR.

[maharmstone]

Thanks - if you can merge it as it is for now, that'd be great.

I can't do anything about OS X or ARM, but the Linux version compiles alright on my Gentoo box, so it must be something minor - I'll send through a separate PR once I sort it.

[Rastaban]

If the Linux build failure comes down to a missing dependency that needs to be added to the build machine let me know via an issue.