Make static lexical deserialization lazier.

Only deserialize on first usage of a particular lexical now. Cache it
so future lookups are fast. Much work in this patch by timotimo++.
bytecode dumping has to finish frames before poking around in them
Lazily deserialize method caches.

Saves another ~8MB off base memory for Rakudo.
Enable code objects to be lazily deserialized.

We now can attach the indexes to a MAST::Frame, and keep them around
until such a time as we need the code object. The goal is that, in
conjunction with some other improvements, we might be able to avoid
deserializing many code objects in Perl 6, along with signatures,
parameters, etc.
Correct comp unit mutex setup.
Merge remote-tracking branch 'origin/master' into moar-jit

Conflicts:
	src/6model/6model.c