Fix broken assumptions in LocalePicker.

This code assumed that the locale is always 5 chars in
length and was of the form xx-YY. This is not necessarily
true. The language can be 3 letters in length and the locale
might have a script and variant.

Also cleans up several nasty pieces of code and eliminates
unnecessary array copies and improves readability by using
idiomatic java.

bug: 15873165
bug: 10090157

Change-Id: Iab1cfd7b78e5772b1245654f2153caf63a96033d
Fall back to "tl" if "fil" is absent.

For JB-MR1, there was a hack that used "tl" where
we really meant "fil" because ICU didn't have localizations
for "fil". This has now been fixed, and we now support 3 letter
language codes for AAPT so we can use "fil" where required.

For the benefit of apps that need to target older platforms,
we fall back to "tl" if the app has assets for "tl" and the
resource locale is "fil".

See bugs 7291355, 7207176 and 8049507 for more context.

Change-Id: I1ac8502525f99b40f9091d5efd2df33518d47a41