Remove MicroWindows support.

MicroWindows (aka Nano-X) support hasn’t been updated since 2010 and last work for it in wxWidgets happened more than 10 years ago.

src/univ/scrolbar.cpp

@@ -43,7 +43,7 @@
     #define WXDEBUG_SCROLLBAR
 #endif
 
-#if defined(WXDEBUG_SCROLLBAR) && defined(__WXMSW__) && !defined(__WXMICROWIN__)
+#if defined(WXDEBUG_SCROLLBAR) && defined(__WXMSW__)
 #include "wx/msw/private.h"
 #endif
 
@@ -627,7 +627,7 @@ void wxScrollBar::UpdateThumb()
             dc.DrawRectangle(rect);
 
             // under Unix we use "--sync" X option for this
-            #if defined(__WXMSW__) && !defined(__WXMICROWIN__)
+            #if defined(__WXMSW__)
                 ::GdiFlush();
                 ::Sleep(200);
             #endif // __WXMSW__