Implement the CLAP timer-support extension

This is entirely implemented on the Wine side. I'll assume most Windows
plugins will use their own timers instead, but this could be useful for
plugins that try to use the same interface on all platforms.

src/wine-host/utils.cpp

@@ -172,8 +172,6 @@ MainContext::WatchdogGuard MainContext::register_watchdog(HostBridge& bridge) {
 
 void MainContext::async_handle_watchdog_timer(
     std::chrono::steady_clock::duration interval) {
-    // Try to keep a steady framerate, but add in delays to let other events
-    // get handled if the GUI message handling somehow takes very long.
     watchdog_timer_.expires_at(std::chrono::steady_clock::now() + interval);
     watchdog_timer_.async_wait([&](const std::error_code& error) {
         if (error) {