refactor(tray icon): update header definitions (#1221)

src/system_tray.h

@@ -1,8 +1,6 @@
 /**
-* @file system_tray.h
-*/
-// macros
-#if defined SUNSHINE_TRAY && SUNSHINE_TRAY >= 1
+ * @file system_tray.h
+ */
 
 // system_tray namespace
 namespace system_tray {
@@ -30,4 +28,3 @@ namespace system_tray {
   end_tray();
 
 }  // namespace system_tray
-#endif