Do not fix uris inside the system.

When we fix uris by adding the user id they belong to, the extras
of the intent are unpacked and repacked. This must not happen
inside the system process. It happened when ResolverActivity was
handling an activity intent coming from a different user.

BUG:18198630

Change-Id: I869897013bb2e5522584b404e87a8f20e7943b60