base1: Fix long shutdown hang of test-dbus{,-address}
base1: Fix long shutdown hang of test-dbus{,-address}

The `NeverReturn()` call causes that unresponded method call to sit in
dbus-daemon's brain, so that shutting down the GTestDBus waits some 25s
for it to time out. This often causes the 60s timeout to be hit
especially during the i386 valgrind runs.

Avoid this by remembering and queueing up all these calls, and complete
them on shutdown. This happens after a unit test is done with all of its
assertions, so is a race free way of avoiding the timeout.

martinpitt/cockpit,mvollmer/cockpit,cockpit-project/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,martinpitt/cockpit,mvollmer/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit