On a glibc system, EAI_NODATA isn't defined unless _GNU_SOURCE is.  The
recommended thing is to use AC_USE_SYSTEM_EXTENSIONS to get all extensions
defined, but that would require fixups in varous other places, so we go for the
smaller change here.

--- krb5-1.11/src/lib/krb5/os/hostrealm.c
+++ krb5-1.11/src/lib/krb5/os/hostrealm.c
@@ -30,6 +30,9 @@
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+/* We need to have EAI_NODATA and friends declared. */
+#define _GNU_SOURCE
+
 #include "k5-int.h"
 #include "os-proto.h"
 #include "fake-addrinfo.h"
--- krb5-1.11/src/lib/krb5/os/sendto_kdc.c
+++ krb5-1.11/src/lib/krb5/os/sendto_kdc.c
@@ -27,6 +27,9 @@
 /* Send packet to KDC for realm; wait for response, retransmitting
  * as necessary. */
 
+/* We need to have EAI_NODATA and friends declared. */
+#define _GNU_SOURCE
+
 #include "fake-addrinfo.h"
 #include "k5-tls.h"
 #include "k5-int.h"
--- krb5-1.11/src/util/support/fake-addrinfo.c
+++ krb5-1.11/src/util/support/fake-addrinfo.c
@@ -101,6 +101,9 @@
  *   these functions, and throw all this away.  Pleeease?  :-)
  */
 
+/* We need to have EAI_NODATA and friends declared. */
+#define _GNU_SOURCE
+
 #include "port-sockets.h"
 #include "socket-utils.h"
 #include "k5-platform.h"
--- krb5-1.12/src/lib/krad/client.c
+++ krb5-1.12/src/lib/krad/client.c
@@ -27,6 +27,9 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+/* We need to have EAI_NODATA and friends declared. */
+#define _GNU_SOURCE
+
 #include <k5-queue.h>
 #include "internal.h"