Illumos 5745 - zfs set allows only one dataset property to be set at a time

5745 zfs set allows only one dataset property to be set at a time
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Reviewed by: Richard PALO <richard@NetBSD.org>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Approved by: Rich Lowe <richlowe@richlowe.net>

References:

https://www.illumos.org/issues/5745
https://github.com/illumos/illumos-gate/commit/3092556

Porting notes:

• Fix the missing braces around initializer, zfs_cmd_t zc = {"\0"};
• Remove extra format argument in zfs_do_set()
• Declare at the top:
  • zfs_prop_t prop;
  • nvpair_t *elem;
  • nvpair_t *next;
  • int i;
• Additionally initialize:
  • int added_resv = 0;
  • zfs_prop_t prop = 0;
• Assign 0 install of NULL for uint64_t types.
  • zc->zc_nvlist_conf = '\0';
  • zc->zc_nvlist_src = '\0';
  • zc->zc_nvlist_dst = '\0';

Ported-by: kernelOfTruth kerneloftruth@gmail.com
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3574