Attempt to fix bug 5684

Attempt to fix bug 5684

With the ctdb checkin dde9f3f006 tdb optimized out write lock checks for
write-enabled transaction. Sadly, this also removed the possibility to ever
remove dead records left over from tdb_delete calls within a transaction.

Tridge, please check this! Did dde9f3f006 have any reason beyond performance
optimizations?

Thanks,

Volker
(cherry picked from commit 3f884c4ae36f3260e63626bdd4989d9258ae6497)
(This used to be commit 1d85e0647e287d269b3f6b534da88f497d6f76c3)