Locales of the form 'lang_Script' where 'Script' is not the
likely script for 'lang' should have 'root' as their parent
locale. For example, the parent of 'az_Arab' should not be
computed as 'az' by truncating from the end, but should be
'root' instead as 'Arab' is not the likely script for 'az'.

The list of such languages was previously specified using
an explicit 'locales' attribute. It is now handled dynamically
using the new 'localeRules' attribute.