dep and rdep on virtual/libbluetooth and VIRTUAL_RUNTIME_*, respectively

Signed-off-by: Fahad Arslan <fahad_arslan@mentor.com>
Introduce virtual/libbluetooth and switch from bluez4 to bluez5

Compatible libbluetooth implementations now provide virtual/libbluetooth
and we specify our preference using PREFERRED_PROVIDER_virtual/libbluetooth
in bluetooth.conf.
Also, we are setting bluez5 as default and blacklisted bluez4 to be sure.

Signed-off-by: Fahad Arslan <fahad_arslan@mentor.com>