Fix clang build on Windows prior to 1.0.0?

[Jan Matyáš]

Hi all,


  1.
Would you like to fix OpenOCD build using clang build on Windows prior to 
release 1.0.0? The minor changes needed are here: 
https://review.openocd.org/c/openocd/+/9506
  2.
To catch future issues of a similar nature, could Windows clang build be added 
to the Gerrit CI? Who has the permissions to do that, and what steps need to be 
taken? Can I help with that somehow?

Thank you,
Jan