Revert "skins2(X11): add missing <limits.h>"

This reverts commit e209d40a.
This is not needed anymore because of the previous commit.

modules/gui/skins2/x11/x11_factory.cpp

@@ -28,7 +28,6 @@
 #include <dirent.h>
 #include <sys/stat.h>
 #include <X11/Xlib.h>
-#include <limits.h>
 
 #include "x11_factory.hpp"
 #include "x11_display.hpp"

modules/gui/skins2/x11/x11_window.cpp

@@ -25,7 +25,6 @@
 #ifdef X11_SKINS
 
 #include <X11/Xatom.h>
-#include <limits.h>
 
 #include "../src/generic_window.hpp"
 #include "../src/vlcproc.hpp"