>> I have done a full rebuild, and having looked more at the structure of libtool.m4 I am now convinced that having that line outside of the scope of _LT_DARWIN_LINKER_FEATURES is simply wrong (probably a copy-pasto or leftover from earlier code).
>> Having rebuilt everything, it only manifests itself in fixincludes/ChangeLog. Iain is traveling right now, but when he is back I would like to submit this patch if he agrees with the above. It was regtested on x86_64-apple-darwin21.

With the correct patch attached.