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/xtistrm.cpp

@@ -160,7 +160,7 @@ void wxObjectWriter::WriteAllProperties( const wxObject * obj, const wxClassInfo
         }
         else
         {
-            wxLogError( _("Create Parameter %s not found in declared RTTI Parameters"), name.c_str() );
+            wxLogError( _("Create Parameter %s not found in declared RTTI Parameters"), name );
         }
         map.erase( name );
     }