[gtksourceview] (3 commits) Non-fast-forward update to branch wip/gsv-next

[Sébastien Wilmet <swilmet src gnome org>]

The branch 'wip/gsv-next' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  b7b016f... build: make installed tests parallel installable

Commits added to the branch:

  958dcb3... build: add missing git.mk include (*)
  1dd3790... build: make installed tests parallel installable
  21b3d5e... Move unit tests to testsuite/ directory

(*) This commit already existed in another branch; no separate mail sent