LU-1042 obdfilter: initialize new object timestamp

LU-1042 obdfilter: initialize new object timestamp

Initialize newly-created objects with a/m/ctime = 0, so that however
clients modify the timestamp it will be updated the first time.  The
fsfilt_ext3_setattr() code will special case ctime = 0 for new files
and reset them to the ext4 s_mkfs_time stored in the superblock.

In LU-221 (commit 414251797ed178eec5d431e1f5aa4a889d2b159f) the
timestamps were initialized to (INT_MIN + 24 * 3600) (1901-12-14),
but the use of unsigned on-disk timestamps caused these negative
numbers to be transformed into large positive numbers (debugfs
reports them to be "Tue Jan 19 20:14:08 2038").  Add a fix so that
files with this exact timestamp have the timestamp reset to 0.

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I22f2cd443402c0c524bafaf37c80cad7b6d00c1e
Reviewed-on: http://review.whamcloud.com/2036
Reviewed-by: Johann Lombardi <johann@whamcloud.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>