ui/sdl2: Allow host to power down screen

By default, SDL disables the screen saver which prevents the host from powering
down the screen even if the screen is locked. This results in draining the
battery needlessly when the host isn't connected to a wall charger. Fix that by
enabling the screen saver.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20240512095945.1879-1-shentey@gmail.com>
diff --git a/ui/sdl2.c b/ui/sdl2.c
index 4971963..0a0eb5a 100644
--- a/ui/sdl2.c
+++ b/ui/sdl2.c
@@ -874,6 +874,7 @@
     SDL_SetHint(SDL_HINT_ALLOW_ALT_TAB_WHILE_GRABBED, "0");
 #endif
     SDL_SetHint(SDL_HINT_WINDOWS_NO_CLOSE_ON_ALT_F4, "1");
+    SDL_EnableScreenSaver();
     memset(&info, 0, sizeof(info));
     SDL_VERSION(&info.version);