authd.c 1.4.3 has:

    enum { $_LONGOPT = UCHAR_MAX,       // no short opt value overlap

where $_LONGOPT is not a legal identifier.  This causes the build to
bomb out on ARM.  (I wonder why it doesn't bomb out on other archs.)

Attached patch (which changes $_LONGOPT to PRE_FIRST_LONGOPT) seems
to work for me.  I tried finding out whether there is a mailing list
for authd where to submit this patch, but there doesn't seem to be such
a thing, which is why I'm submitting it directly to bugzilla.  Maybe
you can help.

Thanks for your time.