Fix incorrect relation name in comment of vacuumlazy.c

Author: Masahiko Sawada
Discussion: https://postgr.es/m/CAD21AoBiOiapB7YGbWRfNZji3cs1gkEwv=uGLTemaZ9yNKK1DA@mail.gmail.com

src/backend/access/heap/vacuumlazy.c

@@ -178,7 +178,7 @@ static bool heap_page_is_all_visible(Relation rel, Buffer buf,
 
 
 /*
- *	vacuum_heap_rel() -- perform VACUUM for one heap relation
+ *	heap_vacuum_rel() -- perform VACUUM for one heap relation
  *
  *		This routine vacuums a single heap, cleans out its indexes, and
  *		updates its relpages and reltuples statistics.