fix python wrappers without onelab

Common/GmshMessage.cpp

@@ -582,6 +582,15 @@ int Msg::GetAnswer(const char *question, int defaultval, const char *zero,
     return atoi(ret);
 }
 
+bool Msg::UseOnelab()
+{
+#if defined(HAVE_ONELAB)
+  return _onelabClient ? true : false;
+#else
+  return false;
+#endif
+}
+
 void Msg::InitializeOnelab(const std::string &name, const std::string &sockname)
 {
 #if defined(HAVE_ONELAB)

Common/GmshMessage.h

@@ -85,7 +85,7 @@ class Msg {
   static void InitializeOnelab(const std::string &name, const std::string &sockname="");
   static GmshClient *GetGmshClient(){ return _client; }
   static void FinalizeOnelab();
-  static bool UseOnelab(){ return _onelabClient ? true : false; }
+  static bool UseOnelab();
   static void ExchangeOnelabParameter(const std::string &key,
                                       std::vector<double> &val,
                                       std::map<std::string, std::vector<double> > &fopt,