Freeze break: GDBus hang work-around

[Bastien Nocera <hadess hadess net>]

Hey,

This bug fix looks like it will be necessary for gnome-settings-daemon
until GIO is fixed properly:
https://bugzilla.gnome.org/show_bug.cgi?id=774813

This could have happened in older versions of gnome-settings-daemon,
but we now start plugins as separate binaries, multiplying the chances
of a hang on startup, which would kill the session.

Cheers