Grant permissions to updated system packages

isSystemPackage calls isSysComponentOrPersistentPlatformSignedPrivApp
which checks the uid of the app.

If we call getSystemPackageInfo on an updated system package we get
the info for the original apk installed on the system permission, not
the updated apk.

This original is not a currently registered package, hence it does not
have an uid and reports -1.

Hence if you pass the result of getSystemPackageInfo into
isSysComponentOrPersistentPlatformSignedPrivApp the first check always
triggers which then makes isSystemPackage assume the package is not a
system package.

Fixes: 115854330
Test: Executed steps in the bug (updated gmscore, restarted, tried to
add second user which triggers default grant policy for the second user)

Change-Id: I74745f8985082490a1f770d7682a964518782dd1