More debug output to debug issue with -print-supported-features on Linux

Author: xedin

Sources/PackageModel/Toolchain+SupportedFeatures.swift

@@ -100,10 +100,17 @@ extension Toolchain {
                 )
             }
 
+            print("Root: \(parsedSupportedFeatures)")
+
             let features: JSON = try parsedSupportedFeatures.get("features")
 
+            print("Features: \(features)")
+
+
             let optionalFeatures = (try? features.getArray("optional")) ?? []
 
+            print("OptionalFeatures: \(optionalFeatures), as 'get': \(try? features.get("optional") as JSON)")
+
             let optional: [SwiftCompilerFeature] = try optionalFeatures.map { json in
                 let name: String = try json.get("name")
                 let categories: [String]? = try json.getArrayIfAvailable("categories")