add tray icon (#1035)

src/system_tray.h

@@ -0,0 +1,23 @@
+/**
+* @file system_tray.h
+*/
+// macros
+#if defined SUNSHINE_TRAY && SUNSHINE_TRAY >= 1
+
+// system_tray namespace
+namespace system_tray {
+
+void open_url(const std::string &url);
+void tray_open_ui_cb(struct tray_menu *item);
+void tray_donate_github_cb(struct tray_menu *item);
+void tray_donate_mee6_cb(struct tray_menu *item);
+void tray_donate_patreon_cb(struct tray_menu *item);
+void tray_donate_paypal_cb(struct tray_menu *item);
+void tray_quit_cb(struct tray_menu *item);
+
+int system_tray();
+int run_tray();
+int end_tray();
+
+} // namespace system_tray
+#endif