Fix blkid time diff bug, build binary.

When calculating time diffs, use difftime() instead of risking
integer overflow.  Also build a "blkid" binary.

Bug: 11175082
Change-Id: I23521f45204574bb32f152926401c2cbad93175b
Merge tag 'android-4.4.2_r1' into kitkat

Android 4.4.2 Release 1