Move Cygwin IPPORT_RESERVED overrride to defines.h

Patch from vinschen at redhat.com.

configure.ac

@@ -589,8 +589,6 @@ case "$host" in
 		[Define if you want to disable shadow passwords])
 	AC_DEFINE([NO_X11_UNIX_SOCKETS], [1],
 		[Define if X11 doesn't support AF_UNIX sockets on that system])
-	AC_DEFINE([IPPORT_RESERVED], [0],
-		[Cygwin has no notion of ports only accessible to superusers])
 	AC_DEFINE([DISABLE_FD_PASSING], [1],
 		[Define if your platform needs to skip post auth
 		file descriptor passing])

defines.h

@@ -42,6 +42,19 @@ enum
 # define SHUT_RDWR SHUT_RDWR
 #endif
 
+/*
+ * Cygwin doesn't really have a notion of reserved ports.  It is still
+ * is useful on the client side so for compatibility it defines as 1024 via
+ * netinet/in.h inside an enum.  We * don't actually want that restriction
+ * so we want to set that to zero, but we can't do it direct in config.h
+ * because it'll cause a conflicting definition the first time we include
+ * netinet/in.h.
+ */
+
+#ifdef HAVE_CYGWIN
+#define IPPORT_RESERVED 0
+#endif
+
 /*
  * Definitions for IP type of service (ip_tos)
  */