Initialize NativeLibraryHelper.Handle with |pkg|

to not parse the same apk file again in NativeLibraryHelper.
This will make derivePackageAbi() 2.5x faster. Previously,
derivePackageAbi() took ~330ms to process ~100 system packages
on volantis-userdebug. With this CL, it takes about ~130ms.

Bug: 22063656
Change-Id: I56d7af0ece3030247e2552c34a1007e79279988c