avoid generating empty PyMethodDef array for types (especially closures)

Cython/Compiler/ModuleNode.py

@@ -1820,6 +1820,8 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
             "};")
 
     def generate_method_table(self, env, code):
+        if env.is_c_class_scope and not env.pyfunc_entries:
+            return
         code.putln("")
         code.putln(
             "static PyMethodDef %s[] = {" %

Cython/Compiler/TypeSlots.py

@@ -460,7 +460,10 @@ class MethodTableSlot(SlotDescriptor):
     #  Slot descriptor for the method table.
 
     def slot_code(self, scope):
-        return scope.method_table_cname
+        if scope.pyfunc_entries:
+            return scope.method_table_cname
+        else:
+            return "0"
 
 
 class MemberTableSlot(SlotDescriptor):