Refactoring of 'luaH_newkey'

Function broke in two and some checks moved to the caller. (We may
want to call it without the checks.)

lobject.h

@@ -750,10 +750,9 @@ typedef union Node {
 
 
 /* copy a value into a key */
-#define setnodekey(L,node,obj) \
+#define setnodekey(node,obj) \
 	{ Node *n_=(node); const TValue *io_=(obj); \
-	  n_->u.key_val = io_->value_; n_->u.key_tt = io_->tt_; \
-	  checkliveness(L,io_); }
+	  n_->u.key_val = io_->value_; n_->u.key_tt = io_->tt_; }
 
 
 /* copy a value from a key */