The WinSock library is now loaded at run-time, which means we can

attempt to load WS2 and then fall back to WS1 if that fails. This
should allow us to use WS2-specific functionality to find out the
local system's list of IP addresses, thus fixing winnet-if2lo, while
degrading gracefully back to the previous behaviour if that
functionality is unavailable. (I haven't yet actually done this; I've
just laid the groundwork.)
This checkin _may_ cause instability; it seemed fine to me on
initial testing, but it's a bit of an upheaval and I wouldn't like
to make bets on it just yet.

[originally from svn r3502]

windlg.c

@@ -1,6 +1,3 @@
-#include <windows.h>
-#include <commctrl.h>
-#include <commdlg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <limits.h>
@@ -8,13 +5,15 @@
 #include <ctype.h>
 #include <time.h>
 
-#include "ssh.h"
 #include "putty.h"
-#include "winstuff.h"
+#include "ssh.h"
 #include "win_res.h"
 #include "storage.h"
 #include "dialog.h"
 
+#include <commctrl.h>
+#include <commdlg.h>
+
 #ifdef MSVC4
 #define TVINSERTSTRUCT  TV_INSERTSTRUCT
 #define TVITEM          TV_ITEM