include libudev only on udev builds

platform/x11/joystick_linux.cpp

@@ -33,11 +33,14 @@
 #include "joystick_linux.h"
 
 #include <linux/input.h>
-#include <libudev.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <errno.h>
 
+#ifdef UDEV_ENABLED
+#include <libudev.h>
+#endif
+
 #define LONG_BITS  (sizeof(long) * 8)
 #define test_bit(nr, addr)  (((1UL << ((nr) % LONG_BITS)) & ((addr)[(nr) / LONG_BITS])) != 0)
 #define NBITS(x) ((((x)-1)/LONG_BITS)+1)