Autocheck for snprintf, and use sprintf if it is not available.
Remove declaration of h_errno, since it is supposedly declared in netdb.h.
Changes proposed by itojun.
diff --git a/config.h.in b/config.h.in
index b5c495f..f945535 100644
--- a/config.h.in
+++ b/config.h.in
@@ -509,6 +509,9 @@
 /* Define if you have the sigrelse function.  */
 #undef HAVE_SIGRELSE
 
+/* Define if you have the snprintf function.  */
+#undef HAVE_SNPRINTF
+
 /* Define if you have the statvfs function.  */
 #undef HAVE_STATVFS