Increase timeout for initial XDP portal session to 2s
It should still fail immediately when the portal isn't available, but
in my test VM with systemd automatically activating the portal when it's
first accessed, it can take 800ms or so. Wait for it instead of falling
back after 200ms.
/* This file contains macros that wrap calls to the purple dbus module.
These macros call the appropriate functions if the build includes
dbus support and do nothing otherwise. See "dbus-server.h" for