Illumos #3522

3522 zfs module should not allow uninitialized variables
Reviewed by: Sebastien Roy <seb@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/3522
  illumos/illumos-gate@d5285cae91

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

Porting notes:

1. ZFSOnLinux had already addressed many of these issues because of
   its use of -Wall. However, the manner in which they were addressed
   differed. The illumos fixes replace the ones previously made in
   ZFSOnLinux to reduce code differences.

2. Part of the upstream patch made a small change to arc.c that might
   address zfsonlinux/zfs#1334.

3. The initialization of aclsize in zfs_log_create() differs because
   vsecp is a NULL pointer on ZFSOnLinux.

4. The changes to zfs_register_callbacks() were dropped because it
   has diverged and needs to be resynced.

module/zfs/vdev_raidz.c

@@ -1190,7 +1190,8 @@ vdev_raidz_matrix_reconstruct(raidz_map_t *rm, int n, int nmissing,
 	uint64_t ccount;
 	uint8_t *dst[VDEV_RAIDZ_MAXPARITY];
 	uint64_t dcount[VDEV_RAIDZ_MAXPARITY];
-	uint8_t log = 0, val;
+	uint8_t log = 0;
+	uint8_t val;
 	int ll;
 	uint8_t *invlog[VDEV_RAIDZ_MAXPARITY];
 	uint8_t *p, *pp;