Fixed rtkit feature guard

src/core/linux/SDL_threadprio.c

@@ -30,8 +30,9 @@
 #include <pthread.h>
 #include "SDL_system.h"
 
-#if HAVE_DBUS_DBUS_H
 #include "SDL_dbus.h"
+
+#if SDL_USE_LIBDBUS
 /* d-bus queries to org.freedesktop.RealtimeKit1. */
 #define RTKIT_DBUS_NODE "org.freedesktop.RealtimeKit1"
 #define RTKIT_DBUS_PATH "/org/freedesktop/RealtimeKit1"