ZTS: Fix attach-o_ashift.ksh for multiple platforms

The `-o ashift` option must appear after attach to be properly
interpreted by getopt(3) on all platforms.

Reviewed-by: Richard Elling <[email protected]>
Reviewed-by: Kjeld Schouten <[email protected]>
Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Ryan Moeller <[email protected]>
Signed-off-by: Igor Kozhukhov <[email protected]>
Closes #9636

tests/zfs-tests/tests/functional/cli_root/zpool_attach/attach-o_ashift.ksh

@@ -92,7 +92,7 @@ typeset badvals=("off" "on" "1" "8" "17" "1b" "ff" "-")
 for badval in ${badvals[@]}
 do
 	log_must zpool create $TESTPOOL1 $disk1
-	log_mustnot zpool attach $TESTPOOL1 -o ashift=$badval $disk1 $disk2
+	log_mustnot zpool attach -o ashift=$badval $TESTPOOL1 $disk1 $disk2
 	log_must zpool destroy $TESTPOOL1
 	log_must zpool labelclear $disk1
 	log_mustnot zpool labelclear $disk2