mariadb: add perl and perl modules to RDEPENDS

Perl and perl modules don't be installed in small image, but mariadb-server, mariadb-client
and mariadb-leftovers need them in runtime, so we add them to RDEPENDS.

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Chong Lu <Chong.Lu@windriver.com>