record format without requiring the doubly linked list added by
Heikki in ChangeSet@1.1627.16.2


innobase/btr/btr0sea.c:
  btr_search_drop_page_hash_index(): support the compact record format
innobase/ibuf/ibuf0ibuf.c:
  ibuf_insert_to_index_page(): Remove unnecessary computation of
  field offsets.
innobase/row/row0ins.c:
  row_ins_index_entry_low(): Remove unnecessary computation of
  field offsets.