added Win64 detection

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@23816 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/platform.h

@@ -43,6 +43,21 @@
 #    endif
 #endif
 
+#if defined(_WIN64)
+#    ifndef _WIN32
+        /*
+            a lot of code (mistakenly) uses #ifdef _WIN32 to either test for
+            Windows or to test for !__WIN16__, so we must define _WIN32 for
+            Win64 as well to ensure that the existing code continues to work.
+         */
+#       define _WIN32
+#   endif /* !_WIN32 */
+
+#   ifndef __WIN64__
+#       define __WIN64__
+#   endif /* !__WIN64__ */
+#endif /* _WIN64 */
+
 #if defined(_WIN32) || defined(WIN32) || defined(__NT__) || defined(__WXWINCE__)
 #    ifndef __WXMSW__
 #        define __WXMSW__