perl: refactor configure step

After discussion with Perl-Cross's author (Alex Suykov)

Note: Using -A with variables that aren't option lists makes little sense.

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Tested-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>