Bug 9890 - Fix the new plugin system for package installs

Create the plugins directory in the Makefile

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
One line change, all ok.
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Merge branch 'bug_9890' into 3.12-master