Fixed conditional signing based upon the modification time.
Fixed conditional signing based upon the modification time.

Fixed the inverted for condition to sign the APK if the source
(unsigned) APK is newer than the target (signed) APK.

Tested:
Built and signed fplutil example project.  Touched file in example
project, built again and verified the signed APK is updated.

Bug: 18205479
Change-Id: I7fe57cd32f20a5eb88e2c8dc84e97b1a7e17e4a2

google/fplutil,google/fplutil,google/fplutil,google/fplutil,google/fplutil,google/fplutil