Fix compilation of generic renderer DrawGauge() in non-PCH build.

Include "wx/msw/wrapwin.h" explicitly to get the declaration of MulDiv()
needed since the changes of r77748.

Closes #16577.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77882 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/renderg.cpp

@@ -42,6 +42,11 @@
     #include "wx/osx/private.h"
 #endif
 
+#ifdef __WINDOWS__
+    // We only need it to get ::MulDiv() declaration, used by wxMulDivInt32().
+    #include "wx/msw/wrapwin.h"
+#endif
+
 // ----------------------------------------------------------------------------
 // wxRendererGeneric: our wxRendererNative implementation
 // ----------------------------------------------------------------------------