swift234

Invalidate the call graph at the end of several passes.

Without further changes to maintain the call graph, these passes all
break the call graph once it tracks potential calls to
deinits (e.g. from strong_release, etc.).

I measure approximately 1.3% increase in stdlib build time with this
change.

The compile-time cost of this change will be reduced with forthcoming
changes to allow invalidating only the portion of the call graph for a
single function.