swift

e5751afd - [test] Verify usage of swift_feature_ markers without enabling features

[test] Verify usage of swift_feature_ markers without enabling features When a feature is removed from `Features.def` or when a test removes all usages of `-enable-experimental/upcoming-feature` keeping the `REQUIRES:` lines around is probably a mistake. Warn about possibly missing flags if a `REQUIRES:` is found referencing a feature without the equivalent `-enable-*-feature` in a `RUN:` line.