remove duplicate definitions of INET[6]_ADDRSTRLEN

these were leftover from early beginnings when arpa/inet.h was not
including netinet/in.h.

include/arpa/inet.h

@@ -24,11 +24,6 @@ struct in_addr inet_makeaddr(in_addr_t, in_addr_t);
 in_addr_t inet_lnaof(struct in_addr);
 in_addr_t inet_netof(struct in_addr);
 
-#undef INET_ADDRSTRLEN
-#undef INET6_ADDRSTRLEN
-#define INET_ADDRSTRLEN  16
-#define INET6_ADDRSTRLEN 46
-
 #ifdef __cplusplus
 }
 #endif

include/netinet/in.h

@@ -60,8 +60,6 @@ struct ipv6_mreq {
 
 extern const struct in6_addr in6addr_any, in6addr_loopback;
 
-#undef INET_ADDRSTRLEN
-#undef INET6_ADDRSTRLEN
 #define INET_ADDRSTRLEN  16
 #define INET6_ADDRSTRLEN 46