editors/emacs-devel: Update to 2021-12-05 commit, 2d0e1e5

This update fixes a bug that caused "Unknown button type
‘help-function’" errors such as
https://portsfallout.com/fallout/421603/.

See upstream bug https://debbugs.gnu.org/cgi/bugreport.cgi?bug=52291 and
the fix in
https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=5404973916dc5d0b92604d31ad7dca2358bc5b9a.