this gets us through CORE.setting. but it's probably wrong.

at the very least p6captureouters is not correct this way.
Revert incorrect MVM_is_null additions.

It should only be used on MVMObject.
Some more MVM_is_null in perl6_ops.c.

This should be all of them; the current bug in setting compilation is
most likely to be something missing in Moar.
Add missing MVM_is_null in p6capturelex.

With this, we make it thorugh the setting build again.
Merge branch 'vm-null' into nom
Bump for a Moar with VMNull support.