Bug 1143639: Store pointer to |handle_pdu| in |io_state| structure
Bug 1143639: Store pointer to |handle_pdu| in |io_state| structure

The |handle_pdu| function processes incoming PDUs. A pointer to this
function is now stored in the |io_state| structure. Only command
sockets receive PDUs, so the pointer is NULL for notification sockets.

BruceSunMozilla/platform_system_bluetoothd,mozilla-b2g/platform_system_bluetoothd,tdz/platform_system_bluetoothd,hobinjk/platform_system_bluetoothd,hobinjk/system-bluetoothd,andyvand/platform_system_bluetoothd