add old openssh fuction xfree

xmalloc.c

@@ -49,6 +49,14 @@ xmalloc(size_t size)
 	return ptr;
 }
 
+void
+xfree(void *ptr)
+{
+	if (ptr == NULL)
+		fatal("xfree: NULL pointer given as argument");
+	free(ptr);
+}
+
 void *
 xcalloc(size_t nmemb, size_t size)
 {

xmalloc.h

@@ -18,6 +18,7 @@
 
 void	 ssh_malloc_init(void);
 void	*xmalloc(size_t);
+void     xfree(void *);
 void	*xcalloc(size_t, size_t);
 void	*xreallocarray(void *, size_t, size_t);
 char	*xstrdup(const char *);