Minor mop-up for List improvements.

Fix a few places that were using written-out versions of the
pg_list.h macros that commit cc99baa4 just improved, making them
also use those macros so as to gain whatever performance improvement
is to be had.

Discussion: https://postgr.es/m/CAApHDvpo1zj9KhEpU2cCRZfSM3Q6XGdhzuAS2v79PH7WJBkYVA@mail.gmail.com

src/backend/catalog/objectaddress.c

@@ -1506,7 +1506,7 @@ get_object_address_attribute(ObjectType objtype, List *object,
 		ereport(ERROR,
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("column name must be qualified")));
-	attname = strVal(lfirst(list_tail(object)));
+	attname = strVal(llast(object));
 	relname = list_truncate(list_copy(object), list_length(object) - 1);
 	/* XXX no missing_ok support here */
 	relation = relation_openrv(makeRangeVarFromNameList(relname), lockmode);

src/backend/commands/sequence.c

@@ -1668,7 +1668,7 @@ process_owned_by(Relation seqrel, List *owned_by, bool for_identity)
 
 		/* Separate relname and attr name */
 		relname = list_truncate(list_copy(owned_by), nnames - 1);
-		attrname = strVal(lfirst(list_tail(owned_by)));
+		attrname = strVal(llast(owned_by));
 
 		/* Open and lock rel to ensure it won't go away meanwhile */
 		rel = makeRangeVarFromNameList(relname);

src/backend/nodes/list.c

@@ -327,7 +327,7 @@ lappend(List *list, void *datum)
 	else
 		new_tail_cell(list);
 
-	lfirst(list_tail(list)) = datum;
+	llast(list) = datum;
 	check_list_invariants(list);
 	return list;
 }
@@ -345,7 +345,7 @@ lappend_int(List *list, int datum)
 	else
 		new_tail_cell(list);
 
-	lfirst_int(list_tail(list)) = datum;
+	llast_int(list) = datum;
 	check_list_invariants(list);
 	return list;
 }
@@ -363,7 +363,7 @@ lappend_oid(List *list, Oid datum)
 	else
 		new_tail_cell(list);
 
-	lfirst_oid(list_tail(list)) = datum;
+	llast_oid(list) = datum;
 	check_list_invariants(list);
 	return list;
 }
@@ -459,7 +459,7 @@ lcons(void *datum, List *list)
 	else
 		new_head_cell(list);
 
-	lfirst(list_head(list)) = datum;
+	linitial(list) = datum;
 	check_list_invariants(list);
 	return list;
 }
@@ -477,7 +477,7 @@ lcons_int(int datum, List *list)
 	else
 		new_head_cell(list);
 
-	lfirst_int(list_head(list)) = datum;
+	linitial_int(list) = datum;
 	check_list_invariants(list);
 	return list;
 }
@@ -495,7 +495,7 @@ lcons_oid(Oid datum, List *list)
 	else
 		new_head_cell(list);
 
-	lfirst_oid(list_head(list)) = datum;
+	linitial_oid(list) = datum;
 	check_list_invariants(list);
 	return list;
 }