Simplify OBJ_obj2nid()

Simplify OBJ_obj2nid()

Continue with OBJ_bsearch_() elimination.

OBJ_obj2nid() first checks if the object identifier passed in has a nid
and if so, it returns that. Otherwise, it looks into the global hash of
added objects (of course without locking) for a match and then returns
the nid thereof. As a last attempt, it searches the table of built-in
object identifiers.

The last two steps can be cleaned up and simplified quite a bit by using
C99 initializers, bsearch() and an appropriate comparison function. Then
it becomes obvious that bsearch() already returns a pointer to the nid
we're looking for, so there is no point in converting that into its
corresponding obj and returning the nid thereof.

ok jsing