Fix a bug in insert buffer B-tree upper levels; probably caused the crash by B.Fitzpatrick
buf0flu.c:
  Fix a bug in previous change
  A small optimization for LRU flushes to avoid losing hot pages from the buffer pool


innobase/buf/buf0flu.c:
  Fix a bug in previous change
innobase/dict/dict0dict.c:
  Fix a bug in insert buffer B-tree upper levels; probably caused the crash by B.Fitzpatrick
innobase/include/dict0dict.h:
  Fix a bug in insert buffer B-tree upper levels; probably caused the crash by B.Fitzpatrick
innobase/btr/btr0btr.c:
  Fix a bug in insert buffer B-tree upper levels; probably caused the crash by B.Fitzpatrick
innobase/btr/btr0cur.c:
  Fix a bug in insert buffer B-tree upper levels; probably caused the crash by B.Fitzpatrick