Don't notify parents of views made focusable off UI thread

Clickable now implies focusable by default. While views are
only supposed to be modified on the UI thread, before O
this wasn't enforced when setting a view as clickable. Now,
it is enforced by virtue of clickable setting focusable for
auto-focusable views.

In order to prevent crashes, detect this situation for pre-O
target-sdks and skip notifying parents of a view made
focusable if:
- it was made focusable by the new auto-focusable mechanic.
- and this is occuring off the UI thread.

The net result in these cases will be a newly-focusable view
that won't immediately receive focus if it was supposed to
(though this will be exceedingly rare).

Bug: 34815147
Test: Verified that the crashing app in the bug (JWLibrary)
      doesn't crash after this change.
Change-Id: I90e9a082cb1e1a3fec75ae5159f2f2c8540ffdc2