Register the Wine host bridge watchdog

It doesn't do anything yet.

src/wine-host/bridges/common.cpp

@@ -22,7 +22,8 @@ HostBridge::HostBridge(MainContext& main_context,
                        boost::filesystem::path plugin_path)
     : plugin_path(plugin_path),
       main_context(main_context),
-      generic_logger(Logger::create_wine_stderr()) {}
+      generic_logger(Logger::create_wine_stderr()),
+      watchdog_guard(main_context.register_watchdog(*this)) {}
 
 void HostBridge::handle_win32_events() {
     MSG msg;

src/wine-host/bridges/common.h

@@ -125,4 +125,11 @@ class HostBridge {
      * @see Logger::create_wine_stderr
      */
     Logger generic_logger;
+
+   private:
+    /**
+     * A guard that, while in scope, will cause `shutdown_if_dangling()` to
+     * periodically be called.
+     */
+    MainContext::WatchdogGuard watchdog_guard;
 };