Index: b/usr/src/lib/libresolv/resolv.h
===================================================================
--- a/usr/src/lib/libresolv/resolv.h
+++ b/usr/src/lib/libresolv/resolv.h
@@ -43,6 +43,14 @@
 
 #include <stdio.h>
 
+/* from /usr/include/netinet/in.h.  */
+#if !defined(IN_SET_LOOPBACK_ADDR)
+#define IN_SET_LOOPBACK_ADDR(a) \
+        { (a)->sin_addr.s_addr  = htonl(INADDR_LOOPBACK); \
+        (a)->sin_family = AF_INET; }
+#endif
+
+
 #ifdef	__cplusplus
 extern "C" {
 #endif