Tweaks to file:// Uri StrictMode checks.

Whitelist two more legacy intent actions, and don't enforce the
StrictMode checks when resolving intents that might be coming from
legacy apps.  Newer apps would have already been yelled at directly
before getting to the resolver.

Bug: 26976516, 26977622
Change-Id: Ibf72a361ed68c52cfaac16c32ab40e79005a42e7