buildroot

host-perl: export and rename PERL5LIB

The official Perl documentation refers only to PERL5LIB.
PERLLIB is obsolete, we don't need to be compatible with Perl4.

PERL5LIB is used in all environment, so it is simpler to just export it.

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>