OpenZFS on OS X

* mount error -1 fix

There are two problems with mount error -1.
1st: 1.9.4 pools using crypto, needs to have features enabled, but error message is poor.
Update the error message.

2nd: Some 2.0 versions missed projectquotas in crypto, so we've added a temporary work
around so you can mount it, you will see error on "<0:0>". Run scrub to clear it.


zfs-2.0.0rc4-4-g3841016507


* Fix zstd (actually compress)
* Better set thread priorities
* Fix kstat panic
* New zpool import (test it works?)
* xattr fixes
* Fix ARC tunables to actually work
* Fix *objquotas (mount -1 error)

There appears to be an issue with import : we need more information for this one to solve it.

There is an issue with using crypto from 1.9.4, it will not mount these datasets.