Add LocaleList support to Paint and TextView.

This keeps the existing single-locale APIs working (and adds
parameter annotations to them), while adding an API for setting and
getting the whole locale list.  At the moment, the implementation
ignores the actual data in the locale list except for its primary
locale.

Also add a method to LocaleList to return the system's default locale
list. (Currently a one-member list just containing the system
default locale.)

Change-Id: Icea9d164ddae51f50dd71e18b5d91c96f233b8b8