losetup: assorted fixes. Closes 6314

"losetup -d" was not complaining that LOOPDEV is missing.
"losetup -a" was listing only up to /dev/loop9.
"losetup -f" looped forever if llop0 was taken, and never tried
anything after /dev/loop9.
"-o" with other options (say, -r) had no effect.

function                                             old     new   delta
losetup_main                                         376     419     +43

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2 files changed