Compile plugins before recreating docs
Compile plugins before recreating docs

Summary:
This explicit dependency solves both parallel build conditions reported
in and therefore fixes T849.  Parts of make doc need the plugins (the
plugin documentation) to proceed.

Test Plan:
I have executed the make commands with the correction in place
on the system that reliably exhibited the error in both conditions
plus one more system. Without the change, make fails, with the change,
it succeeds.

Reviewers: pmaanen, MaxZ

Reviewed By: pmaanen

Subscribers: #openmha

Maniphest Tasks: T849

Differential Revision: https://dev.openmha.org/D309

HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA