Fix excludes logic for included modules.

See ruby/test_struct.rb for one such example. Test methods pulled
in from a module were not firing exclude logic, inflating our
failure rate on the updated 2.2 tests. With this fix, about 30
failures went back underground.
Update tags for #2142.
Add frozen string optz and improve string handling in JIT.

* FrozenString operand represents "str".freeze
* All modes cache frozen strings and bytelists now (none before)