Fix STR #2569 cont'd: put back MSWindows version of Fl_Native_File_Chooser::filters()

that had been erroneously removed by r.8378 that merged include files (it was
previously an inline function).

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@8454 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

src/Fl_Native_File_Chooser_WIN32.cxx

@@ -821,6 +821,10 @@ const char* Fl_Native_File_Chooser::preset_file() const {
   return(_preset_file);
 }
 
+int Fl_Native_File_Chooser::filters() const {
+  return(_nfilters);
+}
+
 char *wchartoutf8(LPCWSTR in)
 {
   static char *out = NULL;