swift234

Sema: 'dynamic' attribute now diagnoses if Foundation is not imported

This prevents us from seeing a less useful error message from SILGen
further down the line.

Also fix a bug where @objc without importing Foundation was not diagnosed
after the first top-level form. Some tests were relying on this behavior,
so fix those tests, either by splitting off the objc parts of the test, or
just by passing the -disable-objc-attr-requires-foundation-module flag.

Fixes <rdar://problem/20660270>.

Swift SVN r29359