configure: restore backward compatibility

configure: restore backward compatibility

Commit a9c3d70d902a0473ee5c13336317006a52ce8242 broke backward compatibility
by making 'configure' error out if parameters are passed, instead of
ignoring them.
Sometimes packaging systems detect 'configure' and assume it's from
autotools, and pass a bunch of options. Eg:

 dh_auto_configure
	./configure --build=x86_64-linux-gnu --prefix=/usr --includedir=${prefix}/include --mandir=${prefix}/share/man --infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var --disable-option-checking --disable-silent-rules --libdir=${prefix}/lib/x86_64-linux-gnu --runstatedir=/run --disable-maintainer-mode --disable-dependency-tracking

Ignore unknown options again instead of erroring out.

Fixes: a9c3d70d902a ("configure: add options ability")
Signed-off-by: Luca Boccassi <bluca@debian.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>