perl-cross: bump to version 0.9.4

this release fixes the build when BR2_PREFER_STATIC_LIB
see http://autobuild.buildroot.net/results/057/057a4b9976fd6b9c5cddd117a3f29de51efe719f/build-end.log
see https://github.com/arsv/perl-cross/issues/11

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>