Fix dev time initialization for cache age caculation

dev->bid_time was initialized to INT_MIN causing an
overflow in cache age calculation, which in turn
caused a new device structure to not be filled with
data due to assumed up-to-date values.

Change-Id: I232e0a57d52777cf0ae6f5f7d01cbf8601a9011f
blkid: Add support for probing exFAT

 * e2fsprogs can't currently detect exFAT filesystems.
 * Apply patch from GoogleTV to add support.

Change-Id: Ib08bdb1d13e995d133a62539e3bfa0e3a22eeead