fix Makefile.in

- unify ~all gbuild targets to one gbuild call
- kill CHECK_PARALLELISM as we dont respect it consistently anyway
- ${MODULE}.subsequentcheck needs no specialcasing now anymore too
- should fix e.g. "make unitcheck slowcheck subsequentcheck" calls

Change-Id: I4238d7de599cb9fbaf09f60539d6655b85b87c29
Reviewed-on: https://gerrit.libreoffice.org/6722
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Reviewed-by: Björn Michaelsen <bjoern.michaelsen@canonical.com>
Tested-by: Björn Michaelsen <bjoern.michaelsen@canonical.com>