Git commits in Moodle 3.4.2 by sam marshall

commit 283f265fbeffbf56fab13fc2a075732c8e92777e
Author: sam marshall <s.marshall@open.ac.uk>
Date:   Tue, 30 Jan 2018 01:16:06 +0800
Tag:    v3.4.2

MDL-61305 Performance: Modinfo cache can get built in parallel