Prior to commit 063c23d9, we were tracking a list of parallel
qtest objects, in order to safely clean up a SIGABRT handler
only after the last connection quits.  But when we switched to
more of glib's infrastructure, the list became dead code that
is never assigned to.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>