Make QtDBus work again with D-Bus 1.0 and 1.1

Make QtDBus work again with D-Bus 1.0 and 1.1

The dbus_get_version function was introduced in 1.2, so we'd need to
detect pre-1.2 by the absence of the function. But if we're going to
detect the presence or absence of any function, we might as well do it
on dbus_connection_can_send_type, which is the function we wanted anyway.

Change-Id: I6e17a3a8f1382c6a489490084f6e3f61aa5a1947
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>