[Bug-wget] warning about unknown .wgetrc directives

[Karl Berry]

Giuseppe et al.,

I suggest making unknown .wgetrc directives a warning (and just ignore
them, proceeding on normally), rather than a failure.  For purposes of
compatibility - a person might have a brand-new wget on system A, but
for whatever reason, have to run an older wget on system B.  But it's
convenient to have the same wget regardless.

This came up for us in TeX Live, where we use an "internal" wget to
download stuff -- a user had a new .wgetrc directive, which caused the
(slightly older) wget we had to fail.  It was not a simple thing to
debug, or detect.

best,
karl