Use conditional compilation with OPENSSL_VERSION_NUMBER to support a

certain function that is not in OpenSSL before 0.9.7, but is required
for correct operation after 0.9.7. The technique is from Network
Security with OpenSSL, whose code is at http://www.opensslbook.com/code.html
(see ssl/common.c).

CHANGELOG

@@ -1,5 +1,10 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [Ncat] Made Ncat compile with versions of OpenSSL before 0.9.7. It
+  would fail in ncat_openssl.c with the message "structure has no
+  member named `it'". The problem was reported by Jaroslav Fojtik.
+  [David]
+
 o Tweaked validate_scan_lists so as to handle -SP and -SA at the same time when
   running nmap as nonroot or using IPv6.  It now combines the two port lists
   [Josh Marlow]