fix for crash when a python operator or render engine was freed in the C code and then referenced from python.

now further access in python gives an exception at the line when the freed data is accessed.

source/blender/python/intern/bpy_rna.h

@@ -207,6 +207,7 @@ int pyrna_array_contains_py(PointerRNA *ptr, PropertyRNA *prop, PyObject *value)
 int pyrna_write_check(void);
 void pyrna_write_set(int val);
 
+void pyrna_invalidate(BPy_DummyPointerRNA *self);
 int pyrna_struct_validity_check(BPy_StructRNA *pysrna);
 int pyrna_prop_validity_check(BPy_PropertyRNA *self);