Define /storage as top-level concept, so that we enforce permissions
uniformly. Moves external storage paths from headers to per-device
environment variables. Added missing mount flags, and we no longer
have adb-specific external storage.
Bug: 6925012
Change-Id: Ic7ca953be2f552d3f0ec9e69f89fef751daa1b29
This fixes bug http://b.android.com/18419, which complains about a bogus
error check in the mount command (it also was wrong in the umount command)
and also asks for the mount command to support more than one loopback
device, as mentioned in the FIXME comments in mount.c. This required some
corresponding changes to umount.c
Change-Id: Ib796c70926395e61557e487bad64984d3295d5f3
