stand/zfs: Fix memory leaking on error cases

[imp]

Summary

Now that we return an allocated zfs_devdesc, we have to free it. These
frees were missing from the error cases. In addition, simplify the code
a bit for the out of memory case.

Sponsored by: Netflix

[kevans]

stand/libsa/zfs/zfs.c

406–411

We should probably error-check this as well?

[imp]

stand/libsa/zfs/zfs.c

406–411

yea, and do what I wonder... I'm guessing return ENOMEM... though I need to understand better when path == NULL

[imp]

Turns out path can't be NULL here (it would have been dereferenced in mount()
unconditionally).

So, if strdup returns NULL, bail with ENOMEM after freeing stuff.

[imp]

rebase

[imp]

stand/libsa/zfs/zfs.c

411–416

hmmm, this needs a minor change...

[imp]

path can be null, so cope with that
Also, add a generic exit path for the error case