test: Fix ModuleInterface/synthesized-conformances.swift on visionOS.
Remove a test case that is causing synthesized-conformances.swift to fail when
run on visionOS after https://github.com/swiftlang/swift/pull/91747. The
following test case now fails:
@available(visionOS, unavailable)
public struct Outer {
@available(iOS 18, *)
public enum Inner: Int {
case a
}
}
// Implies this Equatable conformance:
@available(visionOS, unavailable)
@available(iOS 18, *)
extension Outer.Inner : Swift::Equatable {}
References to declarations that were introduced in a later version of iOS in
contexts that are unavailable on visionOS because that is unsound (apps built
for iOS may run unmodified on visionOS). However, the synthesized conformance
above ought to be considered valid since it is also annotated `@available(iOS
18, *)`. Unfortunately, the availability checker doesn't track independent iOS
availability when compiling for visionOS, though, so the conformance is
rejected.
This is expected fallout from https://github.com/swiftlang/swift/pull/91747 so
for now just comment out the test case with a FIXME to reintroduce it later.
Resolves rdar://186150610.
(cherry picked from commit 8d4a070d619d395b3a936c3d9a5acd39482eaf67)