[libglnx] (5 commits) Non-fast-forward update to branch wip/smcv/testing-helpers

[Simon McVittie <smcv src gnome org>]

The branch 'wip/smcv/testing-helpers' 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:

  80d56b4... Move assertion/test utilities to a separate header
  70e8d4b... Backport most of the test convenience helpers from GLib's G

Commits added to the branch:

  7d599d7... backports: Backport G_SPAWN_DEFAULT (*)
  1e9a2ea... backports: Backport G_OPTION_FLAG_NONE, G_OPTION_ENTRY_NULL (*)
  3b12fb6... testlib: Be compatible with ancient GLib by using glnx_clos
  e98826b... Move assertion/test utilities to a separate header
  679df21... Backport most of the test convenience helpers from GLib's G

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