proxy_getaddrinfo: don't use strncpy

the strncpy function is both dangerous and slow.
dangerous because it doesn't do what the naive programmer expects
(bounded strcpy), and slow because it pads the entire bufsize
with zeroes.

src/core.c

@@ -847,7 +847,7 @@ int proxy_getaddrinfo(const char *node, const char *service, const struct addrin
 
 	p->ai_addr = &space->sockaddr_space;
 	if(node)
-		strncpy(space->addr_name, node, sizeof(space->addr_name));
+		snprintf(space->addr_name, sizeof(space->addr_name), "%s", node);
 	p->ai_canonname = space->addr_name;
 	p->ai_next = NULL;
 	p->ai_family = space->sockaddr_space.sa_family = AF_INET;