swift

938e54c1 - Merge pull request #76128 from ian-twilightcoder/unknown-platform-attr_6.0.0

Merge pull request #76128 from ian-twilightcoder/unknown-platform-attr_6.0.0 [cherry-pick release/6.0.0][Sema] Allow unrecognized platforms in @backDeployed and @_originallyDefinedIn