[tlbuild] Patches for mingw

[Naveen M K]

> Because of some as yet unresolved problems, I omitted synctex,
> dvisvgm and xetex from the default set.
For dvisvgm you would need to backport this commit 
https://github.com/mgieseki/dvisvgm/commit/93ff49a917de251259d707f6bec155fe5095040b 
if building using GCC 11.

Also, thoughts about adding a CI/GitHub Action to build + test on MinGW 
like the one present for Linux in this repo 
https://github.com/TeX-Live/texlive-source?

-- Naveen