swift234

Do not inline self-recursive functions into other functions.

Because our optimization pipeline runs the inliner multiple times,
inlining self-recursive functions into other functions can result in
substantial code growth, which results in more code being generated, and
more compile time.

This was exposed by other changes I have to remove call graph updating
from the inliner (which should have resulted in NFC but didn't due to
implicit deserialization).