DESC
Don't open the lockfile O_SYNC.
EDESC

There is no point in open lockfile O_SYNC now that it's not used in jfsck()
(see jfsck-ignore_lockfile.patch).

While at it, also remove the bogus, racy and unneeded access() call before the
open().

This change (the O_SYNC one, the access() is just code cleanup) improves
performance a huge lot because it avoids small writes and seeking all over the
place. For instance, dbench performance with two processes goes from a 2.40
MB/sec to 4.50 MB/sec.