include fix to get winesources to compile again under MSVC

[Rolf Kalbermatter]

Changelog
  - include/windef.h
    This change allows again compilation of a lot of the core files under MSVC.
    For some reasons the MSVC (6.0) precompiler does not consider __declspec to
    be defined although the compiler knows exactly what to do with it.

Rolf Kalbermatter 

Index: include/windef.h
===================================================================
RCS file: /home/wine/wine/include/windef.h,v
retrieving revision 1.86
diff -u -r1.86 windef.h
--- include/windef.h	28 Aug 2003 21:43:35 -0000	1.86
+++ include/windef.h	16 Sep 2003 22:14:36 -0000
@@ -116,7 +116,7 @@
 #ifndef _declspec
 #define _declspec(x)    __ONLY_IN_WINELIB()
 #endif
-#ifndef __declspec
+#if !defined(__declspec) && !defined(_MSC_VER)
 #define __declspec(x)   __ONLY_IN_WINELIB()
 #endif