Snap: Handle SDCard-removed case

* When the storage path has been set to SDCard but the card has been
  removed, there is currently no way to alter the setting and to get your
  cam to work properly again
* Check the writeable-state of the sdcard on startup and fall back
  to using the internal storage in that case
* The startup-flag is used to keep the current behaviour with removed
  SDcards while cam is still active

* Fixes: https://gitlab.com/LineageOS/issues/android/issues/1376

Change-Id: Ib408883a6810693c93488f8a02fe061c56932d1d
1 file changed