www/otrs: update 5.0.14 -> 5.0.18

• update of DBD::mysql to 4.0.42 broke otrs if using utf8 see https://bugs.otrs.org/show_bug.cgi?id=12677

PR: 218391
Changes: https://www.otrs.com/release-notes-otrs-5s-patch-level-15/

		https://www.otrs.com/release-notes-otrs-5s-patch-level-16/
		https://www.otrs.com/release-notes-otrs-5s-patch-level-17/
		https://www.otrs.com/release-notes-otrs-5s-patch-level-18/

Reported by: topical@gmx.net
Approved by: Mikhail Tsatsenko <m.tsatsenko@gmail.com> (maintainer)