swift234

Sema: Get metatypes for type member constraints inside addTypeMemberConstraint.

This eliminates some boilerplate from the call sites where addTypeMemberConstraint is used correctly, fixes bugs where it isn't (viz. in openType, where we were matching secondary archetypes to the metatype types of the associated types rather than to the associated types themselves), and should prevent the same class of bug from being introduced by new type member constraint generators.

Swift SVN r5041