[client] kb: rename key code arrays from xfree86_* to linux_*

We are using Linux key codes defined in input-event-codes.h, not XFree86
stuff.

client/src/config.c

@@ -790,7 +790,7 @@ static char * optScancodeToString(struct Option * opt)
 {
   char * str;
   alloc_sprintf(&str, "%d = %s", opt->value.x_int,
-      xfree86_to_str[opt->value.x_int]);
+      linux_to_str[opt->value.x_int]);
   return str;
 }