swift

5c762b14 - Frontend: Migrate several options to no longer be ignored in swiftinterfaces.

Frontend: Migrate several options to no longer be ignored in swiftinterfaces. Frontend options should only be printed under `swift-module-flags-ignored:` temporarily to prevent condfails for older development compilers that are still in use (as a rule of thumb, swiftinterfaces should be compatible with compilers that are up to 6 months old). None of the frontend flags that are currently categorized as "ignorable" need to be ignorable anymore.