os_linuxbsd.cpp: include `servers/rendering_server.h`

platform/linuxbsd/os_linuxbsd.cpp

@@ -34,6 +34,7 @@
 #include "core/io/dir_access.h"
 #include "main/main.h"
 #include "servers/display_server.h"
+#include "servers/rendering_server.h"
 
 #ifdef X11_ENABLED
 #include "x11/display_server_x11.h"