Fix blkid's last verification logic to work when the system clock is insane

Fix blkid's last verification logic to work when the system clock is insane

Users have reported problems on newly installed systems when the
Macintosh's system clock battery is dead and the hardware clock is
returning a date of 1904.  Turns out there were some bugs in handling
dates before the Unix epoch.

Addresses Red Hat Bug: #182188

probe.c (blkid_verify): Fix the bid_time sanity checking logic,
	so that if last verification time is more recent than the
	current time, or the comparison between the last
	verification time and the current time causes an overflow,
	a device verification will take place.

devname.c (blkid_get_dev): Set the initial bid_time to be
	INT_MIN, to guarantee that blkid_verify will always be run
	even when the system clock is insane.

dev.c (blkid_debug_dump_dev), read.c (debug_dump_dev),
	save.c (save_dev): Fix the printf format for dev->bid_time
	to match the fact that it is an signed type.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>