Replace stat with PERL stat in kasp system test

Replace stat with PERL stat in kasp system test

7249bad7 introduced the -c option to stat(1) command, but BSD systems
do not know about it. Replace the stat(1) command with a PERL script
that achieves the same.

Why PERL? For consistency purposes, there are more places in the
system test where we use the same method.

(cherry picked from commit fe601c5915a2c19c5bdc475476d81b01267e2417)