More preparatory work: remove the <windows.h> include from lots of

source files in which it's no longer required (it was previously
required in anything that included <putty.h>, but not any more).
Also moved a couple of stray bits of exposed WinSock back into
winnet.c (getservbyname from ssh.c and AF_INET from proxy.c).

[originally from svn r2160]

sshbn.c

@@ -799,6 +799,7 @@ unsigned short bignum_mod_short(Bignum number, unsigned short modulus)
 
 void diagbn(char *prefix, Bignum md)
 {
+#ifdef DEBUG
     int i, nibbles, morenibbles;
     static const char hex[] = "0123456789ABCDEF";
 
@@ -816,6 +817,7 @@ void diagbn(char *prefix, Bignum md)
 
     if (prefix)
 	debug(("\n"));
+#endif
 }
 
 /*