eo_base_class: Avoid useless memory alloc

Summary:
The pd->ext will be NULL when the target object on invalidate state or edje object or isolated object etc..

In above case, If data is NULL and ext is not needed, it seems there is no need to create a node.

Reviewers: raster, cedric, Hermet

Reviewed By: Hermet

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D12206

src/lib/eo/eo_base_class.c

@@ -362,6 +362,8 @@ _key_generic_set(const Eo *obj, Efl_Object_Data *pd, const char *key, const void
                }
           }
      }
+   else
+     if (!data) return NULL;
 
    ext = _efl_object_extension_need(pd);
    if (ext)