generic/004: fix filtering of expected error message

The failure message goes to stderr, so we need to redirect stderr to
stdout before running sed.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/004

@@ -58,7 +58,7 @@ $XFS_IO_PROG -T \
 rm ${testfile}
 
 # test creating a r/o tmpfile.  Should fail
-$XFS_IO_PROG -Tr ${TEST_DIR} -c "close" | _filter_test_dir
+$XFS_IO_PROG -Tr ${TEST_DIR} -c "close" 2>&1 | _filter_test_dir
 
 # success, all done
 status=0

tests/generic/004.out

@@ -3,4 +3,4 @@ wrote 4096/4096 bytes at offset 0
 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 4096/4096 bytes at offset 0
 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-/mnt/test: Invalid argument
+TEST_DIR: Invalid argument