9672 Reserve a ZFS replication stream feature flag for ZSTD compression
illumos/illumos-gate@acd7f809f0376580771fe4df8aaeecebe4c40b2f
Author: Allan Jude <allanjude@freebsd.org>
Reviewed by: Matt Ahrens <matt@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>