[Package] Disable availability checking

Author: tonyfreeman

Package.swift

@@ -24,6 +24,7 @@ let package = Package(
                 "URL", "Network", "Stream", "JSON", "DCompression", "Log"
             ],
             swiftSettings: [
+                .unsafeFlags(["-Xfrontend", "-disable-availability-checking"]),
                 .unsafeFlags(["-Xfrontend", "-enable-experimental-concurrency"])
             ]),
     ]
@@ -76,6 +77,7 @@ func addTest(target: String, name: String) {
             dependencies: ["HTTP", "Test"],
             path: "Tests/\(target)/\(name)",
             swiftSettings: [
+                .unsafeFlags(["-Xfrontend", "-disable-availability-checking"]),
                 .unsafeFlags(["-Xfrontend", "-enable-experimental-concurrency"])
             ]))
 }