fix authentication via reverse name

src/proxy.h

@@ -188,7 +188,7 @@ unsigned bandlimitfunc(struct clientparam *param, unsigned nbytesin, unsigned nb
 int scanaddr(const unsigned char *s, unsigned long * ip, unsigned long * mask);
 int myinet_ntop(int af, void *src, char *dst, socklen_t size);
 extern struct nserver nservers[MAXNSERVERS];
-struct nserver authnserver;
+extern struct nserver authnserver;
 unsigned long getip(unsigned char *name);
 unsigned long getip46(int family, unsigned char *name,  struct sockaddr *sa);
 unsigned long myresolver(int, unsigned char *, unsigned char *);