cynara: add exception code for disconnection code.

cynara: add exception code for disconnection code.

For disconnection connections, _dbus_connection_get_dispatch_status_unlocked always returns DBUS_DISPATCH_DATA_REMAINS.
So __bus_loop_dispatch is going around in an infinite loop.
If _dbus_loop_dispatch is out of the loop, _dbus_connection_get_dispatch_status_unlocked returns DBUS_DISPATCH_COMPLETE as normal.

It is dead-lock.

======================  reproduce ==================
su - owner
dbus-send  --type=method_call  --system --dest=org.tizen.system.deviced  /Org/Tizen/System/DeviceD/Display  org.tizen.system.deviced.display.CustomBrightness
dbus-send  --type=method_call  --system --dest=org.tizen.system.deviced  /Org/Tizen/System/DeviceD/Display  org.tizen.system.deviced.display.CustomBrightness
dbus-send  --type=method_call  --system --dest=org.tizen.system.deviced  /Org/Tizen/System/DeviceD/Display  org.tizen.system.deviced.display.CustomBrightness
dbus-send  --type=method_call  --system --dest=org.tizen.system.deviced  /Org/Tizen/System/DeviceD/Display  org.tizen.system.deviced.display.CustomBrightness
dbus-send  --type=method_call  --system --dest=org.tizen.system.deviced  /Org/Tizen/System/DeviceD/Display  org.tizen.system.deviced.display.CustomBrightness
===================================================

Signed-off-by: INSUN PYO <insun.pyo@samsung.com>
Change-Id: I8565a757a62b50a27d2c6b6931e125af452ff74e