Use hardening flags

Signed-off-by: Michael Wild <themiwi@users.sourceforge.net>
Update debian/libplist1.symbols

Signed-off-by: Michael Wild <themiwi@users.sourceforge.net>
Add build-dep on dpkg-dev

Signed-off-by: Michael Wild <themiwi@users.sourceforge.net>
Updated debian/changelog

Git-Dch: Ignore
Signed-off-by: Michael Wild <themiwi@users.sourceforge.net>