Fix bug #5199577 TextView with android:password="true" is showing the "dots"...

Fix bug #5199577 TextView with android:password="true" is showing the "dots" on the left even if the password chars are RTL

- force TextView to LOCALE text heuristic when in "password" mode
- remove TEXT_LAYOUT_DIRECTION_UNKNOWN_DO_NOT_USE
- LocaleUtils.getLayoutDirectionFromLocale() returns "LTR" is locale is NULL or ROOT

Change-Id: I182c46aaf2d73c8b18967fffa230bfabec91ed06