select_tut.2: Diagnose inet_aton() errors with simple fprintf() (not perror())

When it fails, inet_aton() does not set errno, so using
perror() is not appropriate.

Reported-by: Antonio Chirizzi <antonio.chirizzi@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/select_tut.2

@@ -601,7 +601,7 @@ connect_socket(int connect_port, char *address)
     addr.sin_family = AF_INET;
 
     if (!inet_aton(address, (struct in_addr *) &addr.sin_addr.s_addr)) {
-        perror("bad IP address format");
+        fprintf(stderr, "inet_aton(): bad IP address format\\n");
         close(cfd);
         return \-1;
     }