Remove unnecessary c_str() from wx var arg functions arguments

Using c_str() for arguments to wxString::Printf(), Format() and
wxLogXXX() is useless since wx 2.9 days, so simply remove them.

No real changes, this is just a (long due) cleanup.

src/common/msgout.cpp

@@ -203,7 +203,7 @@ void wxMessageOutputLog::Output(const wxString& str)
 
     out.Replace(wxT("\t"), wxT("        "));
 
-    wxLogMessage(wxT("%s"), out.c_str());
+    wxLogMessage(wxT("%s"), out);
 }
 
 #endif // wxUSE_BASE