Another attempt to fix the last remaining build issue.

CoProcessing plugin depends on vtkPVPythonCatalyst. Hence we need to process
that module before we process the plugin.

Change-Id: I5b9841330b52acb9d58dd07585cb155c93376ed6
Merge topic 'catalyst_2.0' into next

8d8fc65 Another attempt to fix the last remaining build issue.