Illumos 6527 - Possible access beyond end of string in zpool comment

6527 Possible access beyond end of string in zpool comment
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Approved by: Gordon Ross <gwr@nexenta.com>

References:
  https://www.illumos.org/issues/6527
  illumos/illumos-gate@2bd7a8d

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>

module/zfs/spa.c

@@ -588,7 +588,6 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
 					error = SET_ERROR(EINVAL);
 					break;
 				}
-				check++;
 			}
 			if (strlen(strval) > ZPROP_MAX_COMMENT)
 				error = SET_ERROR(E2BIG);