Strange warnings when building with uchardet

[Eli Zaretskii]

I've built Groff 1.22.4 today on MS-Windows using MinGW.  The original
build went OK, but then I installed uchardet, reconfigured and
rebuilt.  This time, near the end of the build I saw the following
strange warnings:

       GROFF    doc/meref.ps
     troff: <standard input>:6: warning: macro 'NR' not defined
     troff: <standard input>:28: warning: macro 'TL' not defined
     troff: <standard input>:32: warning: macro 'DE' not defined
     troff: <standard input>:87: warning: macro 'G' not defined
     troff: <standard input>:567: warning: macro 'T' not defined
     troff: <standard input>:653: warning: macro 'ST' not defined
       GROFF    doc/meintro.ps
     troff: <standard input>:12: warning: number register '$1' not defined
     troff: <standard input>:668: warning: macro 'G' not defined
     troff: <standard input>:759: warning: macro 'U' not defined
     troff: <standard input>:992: warning: macro 'T' not defined
     troff: <standard input>:1308: warning: macro 'MO' not defined
       GROFF    doc/meintro_fr.ps
       GROFF    doc/pic.ps

By making yet another fresh build, I verified that these messages are
emitted only when Groff is configured with uchardet, and don't appear
otherwise.  Does anyone here have an idea how these two could be
related?  Should I file a bug report?

(Please CC me on any responses, as I'm not subscribed to this list.)