Generalize bluetooth support so it can be used not only with bluez4 but
with bluez5 as well. Use EXTRA_QMAKEVARS_PRE to pass the packageconfig
options to the do_configure task.
https://jira.digi.com/browse/DEL-2147
Signed-off-by: Javier Viguera <javier.viguera@digi.com>