AIX compilation fixes from Paul Thiessen

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@14233 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/unix/utilsunx.cpp

@@ -1016,8 +1016,9 @@ long wxGetFreeMemory()
 bool wxGetDiskSpace(const wxString& path, wxLongLong *pTotal, wxLongLong *pFree)
 {
 #if defined(HAVE_STATFS) || defined(HAVE_STATVFS)
+    // the case to "char *" is needed for AIX 4.3
     struct statfs fs;
-    if ( statfs(path, &fs) != 0 )
+    if ( statfs((char *)path.fn_str(), &fs) != 0 )
     {
         wxLogSysError("Failed to get file system statistics");