[cdt-dev] Official toolchain support

[Doug Schaefer <cdtdoug@xxxxxxxxx>]

Hey gang, as an update on the efforts to defining a supported set of toolchains, I have added MSYS2 auto-discovery to the MinGW toolchain (in both new and old build systems). I have still a little work there to make sure the 32-bit toolchains are discovered as well.

Also, I had mentioned support for Homebrew on Mac, but at the end of the day, the support is really for the Xcode command-line tools. I don't think supporting the gdb in Homebrew is a good idea since it's not signed properly and is a headache to fix that. 

The good news is that lldb-mi is shipped with Xcode, hidden but it's there. We'll continue working towards making that the supported debugger for Mac.  But the bad news is that means we do not have a supported debug story for Mac at this time.

Of course, Linux is easy, it's whatever gcc, gdb you get from your distro.

Let me know if you have an questions or opinions,

Doug.