As BlueZ 5 introduced backwards incompatible API changes, and we want to
keep support for BlueZ 4 based HFP AG plugin for some time, we need to
separate HFP AG plugin which is based on BlueZ 4 from the one based on
BlueZ 5.
The hfp_ag.c plugin is renamed to hfp_ag_bluez4. This will make it easy
to add an HFP AG plugin for BlueZ 5.
Frédéric Danis