I agree with Lars we want to keep the log parts, but my suggestion was
to just move the setting up of config.log *after* arguments have been
parsed. AFAIR, it is possible to do so and keeping AC_MSG_ERROR uses
because *now* there is some magic in AC_MSG_ERROR (well the AS stuff).
I dislike the code (but I understand very well how you came to it).
Two suggestions then:
1. try what I said (set up AS_MESSAGE_LOG *after* parse-args)
if failed
2. special case $1 == --help, period. Doesn't deserve more.
I.e., don't set up AS_MESSAGE_LOG when $1 == --help. End of the story.