Security fixes for signal handling in GDBus in GLib

[pwithnall (Philip Withnall)]

Due to an unexpected regression when used with IBus (#3353), some follow-up fixes are needed. These will be present in the 2.78.6 and 2.80.2 releases, due out shortly.

The fixes are:

• gdbusconnection: Fix test signal subscription ordering (!4051) · Merge requests · GNOME / GLib · GitLab
• gdbusconnection: Allow name owners to have the syntax of a well-known name (!4053) · Merge requests · GNOME / GLib · GitLab