udev-extraconf: update mount.sh to use /run/media instead of /media
This is done to work around the issue of auto-mounting block devices
(i.e. SD cards) when root filesystem is still in read-only mode and
creating /media/<device> mount-points by udev is not possible. That
is due to udev (/etc/rcS.d/S03udev) getting started earlier than
checkroot (/etc/rcS.d/S10checkroot.sh) gets a chance to re-mount the
rootfs as read-write.
Although, canonical FHS specifies /media/<device> as a mount point
for removable media devices, the latest 2.3 version was released in
2004 and since then FreeDesktop/udisks and other tools adopted the
new /run/media/<user>/<device> location. That was done to overcome
read-only rootfs limitation, since /run is usually a tmpfs mounted
partition, plus avoid name-clash between users.
For our embedded systems environment we assume single-user operation
and hence simplify mount point to just /run/media/<device>. But for
proper per-user mounting to /run/media/<user>/<device>, some sort of
session management is required along with the tool like udisks, that
is out of scope of this simple udev-based auto-mounting.
