Simplify OBJ_sn2nid()

Simplify OBJ_sn2nid()

Another OBJ_bsearch_() elimination.

OBJ_sn2nid() is very similar to OBJ_obj2nid(). First it tries to retrieve
an object identifier with matching "short name" from the global hash of
added objects and then searches the table of built-in objects.

ok jsing