List xml2/curl for macOS linker dependencies

Author: parkera

Package.swift

@@ -142,7 +142,8 @@ let package = Package(
                 "Clibxml2",
             ],
             path: "Sources/_CFXMLInterface",
-            cSettings: interfaceBuildSettings
+            cSettings: interfaceBuildSettings,
+            linkerSettings: [.linkedLibrary("xml2", .when(platforms: [.macOS]))]
         ),
         .target(
             name: "_CFURLSessionInterface",
@@ -151,7 +152,8 @@ let package = Package(
                 "Clibcurl",
             ],
             path: "Sources/_CFURLSessionInterface",
-            cSettings: interfaceBuildSettings
+            cSettings: interfaceBuildSettings,
+            linkerSettings: [.linkedLibrary("curl", .when(platforms: [.macOS]))]
         ),
         .systemLibrary(
             name: "Clibxml2",