fix missing reference for _POSIX_HOST_NAME_MAX on FreeBSD.

FreeBSD declares it in limits.h. Add the proper include.
Signed-off-by: Rafaël Carré <funman@videolan.org>
(cherry picked from commit 62046de3)
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

modules/gui/skins2/x11/x11_window.cpp

@@ -36,6 +36,7 @@
 #include "x11_factory.hpp"
 
 #include <assert.h>
+#include <limits.h>
 
 X11Window::X11Window( intf_thread_t *pIntf, GenericWindow &rWindow,
                       X11Display &rDisplay, bool dragDrop, bool playOnDrop,