use wxStrnlen() and add NULL-checks in wxMsgCatalogFile::FillHash for safer handling of corrupted MO files (closes #3151)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58106 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/internat/internat.cpp

@@ -234,7 +234,8 @@ bool MyApp::OnInit()
     wxLocale::AddCatalogLookupPathPrefix(wxT("."));
 
     // Initialize the catalogs we'll be using
-    m_locale.AddCatalog(wxT("internat"));
+    if (!m_locale.AddCatalog(wxT("internat")))
+        wxLogError(_("Couldn't find/load the 'internat' catalog."));
 
     // this catalog is installed in standard location on Linux systems and
     // shows that you may make use of the standard message catalogs as well