Modifications for query cache + trxs, fix of q.c.+ foreign keys


innobase/include/dict0mem.h:
  Modifications for query cache + trxs, fix of q.c.+ foreign keys
innobase/include/row0sel.h:
  Modifications for query cache + trxs, fix of q.c.+ foreign keys
innobase/include/srv0srv.h:
  Modifications for query cache + trxs, fix of q.c.+ foreign keys
innobase/include/trx0trx.h:
  Modifications for query cache + trxs, fix of q.c.+ foreign keys
innobase/include/trx0trx.ic:
  Modifications for query cache + trxs, fix of q.c.+ foreign keys