IPv6 constants for VC++6 that doesn't have them in the winsock lib

This was SVN commit r153.

source/lib/posix.cpp

@@ -488,6 +488,15 @@ fp_getnameinfo_t getnameinfo;
 fp_getaddrinfo_t getaddrinfo;
 fp_freeaddrinfo_t freeaddrinfo;
 
+/* IPv6 globals
+These are included in the linux C libraries, and in newer platform SDK's, so
+should only be needed in VC++6 or earlier.
+*/
+#if _MSC_VER <= 1200 /* VC++6 or earlier */
+const struct in6_addr in6addr_any=IN6ADDR_ANY_INIT;        /* :: */
+const struct in6_addr in6addr_loopback=IN6ADDR_LOOPBACK_INIT;   /* ::1 */
+#endif
+
 void entry(void)
 {
 // note: winsock header is also removed by this define