generic/269: Fix failure due to race killing fsstress job

When running the test generic/269 against a fast scratch device (loopback
device backed by a file on tmpfs) I often got a test failure due to the
fact that the fsstress job had already completed before the test attempted
to kill it, producing the following failure output:

generic/269 91s ... - output mismatch (see .../generic/269.out.bad)
    --- tests/generic/269.out	2014-11-17 20:59:50.974203000 +0000
    +++ /home/fdmanana/git/hub/xfstests/results//generic/269.out.bad	2015-11-13 15:41:59.669893035 +0000
    @@ -3,3 +3,4 @@
     Run fsstress

     Run dd writers in parallel
    +./tests/generic/269: line 59: kill: (13417) - No such process
    ...
    (Run 'diff -u tests/generic/269.out .../generic/269.out.bad'  to see the entire diff)

So fix this false failure by redirecting the standard output and error
from the kill into the seq file.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/269

@@ -56,7 +56,8 @@ _workout()
 			>> $seqres.full 2>&1
 		sleep $enospc_time
 	done
-	kill $pid
+	echo "Killing fsstress process..." >> $seqres.full
+	kill $pid >> $seqres.full 2>&1
 	wait $pid
 }