[Mac] DllImport must be marked as extern

diff --git a/Source/OpenTK/Platform/MacOS/HIDInput.cs b/Source/OpenTK/Platform/MacOS/HIDInput.cs
index 7ff0e49..382e1f9 100755 (executable)
--- a/Source/OpenTK/Platform/MacOS/HIDInput.cs
+++ b/Source/OpenTK/Platform/MacOS/HIDInput.cs
@@ -819,7 +819,7 @@ namespace OpenTK.Platform.MacOS
                 CFString inCFRunLoopMode);
 
             [DllImport(hid)]
-            public static void IOHIDManagerUnscheduleFromRunLoop(
+            public static extern void IOHIDManagerUnscheduleFromRunLoop(
                 IOHIDManagerRef inIOHIDManagerRef,
                 CFRunLoop inCFRunLoop,
                 CFString inCFRunLoopMode);