FWIW, in case you want to update the ChangeLog entry, I also encountered this failure on gcc 9.3.0. (This commit showed up just as I was about to submit a bug report.)
- Re: [groff] 01/02: [troff]: Fix build failure with Cla... Dave Kemper
- Re: [groff] 01/02: [troff]: Fix build failure wit... G. Branden Robinson