device ID iff the named file is a character or block special device. Otherwise
it is meaningless junk, in which case st_dev should be used. This was done
incorrectly, which could cause mount to display bogus mount info.
-Erik
1) fixed a bug that could crash df, mount, and umount applets if the root
device name was longer then the word "root" (/dev/loop1 vs /dev/root) -
2) severl functions needed static declaration in the umount applet
3) update declaration for function in last_char_is() in libbb
