Cocoa: fix double spaces in CustomControl

https://forum.lazarus.freepascal.org/index.php/topic,70901.0.html

lcl/interfaces/cocoa/cocoacustomcontrol.pas

@@ -331,6 +331,7 @@ begin
      [kVK_Return, kVK_ANSI_KeypadEnter, kVK_Escape, kVK_Space]) then
   begin
     inherited;
+    self.callback.KeyEvHandled;
     exit;
   end;