Fix a race that kept the locale picker from working under heavy CPU load.

The locale picker and the activity transition would both change the
configuration, and depending upon the timing, the activity transition
would undo what the locale picker had just done.  Usually it worked right,
but would often fail if the user changed locales just after a data wipe,
when the media scanner was working hard in the background to index
the contents of the SD card.

http://b/issue?id=2216298