[mac] Add NSColor.LinkColor (#4356) (#4363)

src/appkit.cs

@@ -3906,6 +3906,10 @@ namespace AppKit {
 		[Mac (10,10)]
 		[Static, Export ("quaternaryLabelColor")]
 		NSColor QuaternaryLabelColor { get; }
+
+		[Mac (10, 10)]
+		[Static, Export ("linkColor", ArgumentSemantic.Strong)]
+		NSColor LinkColor { get; }
 		
 		[Mac (10,12)]
 		[Static]

tests/xtro-sharpie/macOS-AppKit.todo

@@ -43,7 +43,6 @@
 !missing-selector! +NSColor::alternatingContentBackgroundColors not bound
 !missing-selector! +NSColor::controlAccentColor not bound
 !missing-selector! +NSColor::findHighlightColor not bound
-!missing-selector! +NSColor::linkColor not bound
 !missing-selector! +NSColor::placeholderTextColor not bound
 !missing-selector! +NSColor::selectedContentBackgroundColor not bound
 !missing-selector! +NSColor::separatorColor not bound