fix compile without OCC

Geo/GModelIO_OCC.cpp

@@ -1558,4 +1558,9 @@ GRegion* GModel::getRegionForOCCShape(const void *shape)
   return 0;
 }
 
+int GModel::importOCCInternals(){
+	Msg::Error("Gmsh must be compiled with Open CASCADE support to query OCC shape");
+  return 0;
+}
+
 #endif

Geo/GModelIO_OCC.h

@@ -103,8 +103,14 @@ public:
   OCC_Internals(){}
   void addVertex(int tag, double x, double y, double z){}
   void addCircleArc(int tag, int tagStart, int tagCenter, int tagEnd){}
+	void addSphere(int tag, double xc, double yc, double zc, double radius){};
   void addThruSections(int tag, std::vector<std::vector<int> > tagEdges){}
   void importOCCInternals(GModel *model){}
+	void applyBooleanOperator(int tag,
+                            std::vector<int> shapeTags[4],
+                            std::vector<int> toolTags[4],
+                            BooleanOperator op,
+                            bool removeShape=true, bool removeTool=true){};
 };
 
 #endif