Move cache_return_entry_w() out of ldbm_back_add when the add is successful.
This change breaks back-bdb2, it needs equvalent changes of those in back-ldbm.

compilation error but likely doesn't resolve sysloging issues).

'make bdb2' tests only BDB2
'make ldbm' tests only LDBM
Fix up scripts (previous changes broke BDB2 testing)

Remove disable write sync (dbcachenowsync) in master (for concurrency test).

suggested by Gerrit Thomson

Move Debug messages outside of c_mutex.  Other LDBM cache codes
also should be streamlined.  Resultant approaches should then
be applied to back-bdb2.

on errno not getting changed by Debug().  Likely a problem elsewhere.
Tests run okay, excepting concurrency has "no such object" problems.

clients).

because it's already done in ldbm_nextkey().