Stop dig complaining about +noidn when it can't IDN

When dig was built without IDN support, it reported an error if the
+noidnin and/or +noidnout options were used. This means the options
were not useful for a script that wants consistent lack of IDN
translation regardless of how BIND is built.

Make dig complain about lack of built-in IDN support only when the
user asks for IDN translation.

Closes #3188

CHANGES

@@ -1,3 +1,6 @@
+5826.	[cleanup]	Stop dig from complaining about lack of IDN support when
+			the user asks for no IDN translation. [GL #3188]
+
 5825.	[funcf]		Set the minimum MTU on UDPv6 and TCPv6 sockets and
 			limit TCP maximum segment size (TCP_MAXSEG) to (1220)
 			for both TCPv4 and TCPv6 sockets. [GL #2201]

bin/dig/dig.c

@@ -1515,8 +1515,11 @@ plus_option(char *option, bool is_batchfile, bool *need_clone,
 				case 'i':
 					FULLCHECK("idnin");
 #ifndef HAVE_LIBIDN2
-					fprintf(stderr, ";; IDN input support"
+					if (state) {
+						fprintf(stderr,
+							";; IDN input support"
 							" not enabled\n");
+					}
 #else  /* ifndef HAVE_LIBIDN2 */
 					lookup->idnin = state;
 #endif /* ifndef HAVE_LIBIDN2 */
@@ -1524,8 +1527,11 @@ plus_option(char *option, bool is_batchfile, bool *need_clone,
 				case 'o':
 					FULLCHECK("idnout");
 #ifndef HAVE_LIBIDN2
-					fprintf(stderr, ";; IDN output support"
+					if (state) {
+						fprintf(stderr,
+							";; IDN output support"
 							" not enabled\n");
+					}
 #else  /* ifndef HAVE_LIBIDN2 */
 					lookup->idnout = state;
 #endif /* ifndef HAVE_LIBIDN2 */