Minimal changeset for AD/MAX devices on latest OpenOCD master branch

[rhempel]

I raised an issue in the MSDK project regarding a possible port of the AD/MAX OpenOCD code to the latest OpenOCD master branch.

analogdevicesinc/msdk#1277

I have made some progress on this topic. I now have an OpenOCD from the upstream master branch with a minimal set of changes from the AD OpenOCD repo. The branch builds under MSYS2 UCRT on Windows and creates an executable that I can use to debug the MAX32690FTHR board.

There are probably a number of features that I have not ported over, mainly because I now have a "modern" version of OpenOCD that works for me for the MAX32xxx and ALL of the other Cortex M devices that I tend to use.

The current state (with a set of notes for building under MSYS2) is here:

https://github.com/rhempel/openocd/tree/adi-merge

Note, this is not by any means a pull request that OpenOCD is likely to take as-is. The commits should be broken down even further to make it clear what is changing, but I thought this would be better done by AD and of course I could assist if needed.

Feedback welcome.