[libglnx] (4 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:

  1d74c0f... testlib: Be compatible with ancient GLib by using glnx_clos
  6e23309... Move assertion/test utilities to a separate header
  50c63d8... Backport most of the test convenience helpers from GLib's G

Commits added to the branch:

  ba51dc2... backports: Backport G_DBUS_METHOD_INVOCATION_HANDLED, _UNHA (*)
  fe50ebb... testlib: Be compatible with ancient GLib by using glnx_clos
  a88d13b... Move assertion/test utilities to a separate header
  247bf07... Backport most of the test convenience helpers from GLib's G

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