MDB_PAGEPERTURB
disable coredump limit
ITS#8011: few corrections for lmdb-backend;

 dn2id.c:
   + assertion for mdb_id2l_insert() result;
   - unnecessary assignment;

 search.c:
   - unused variable 'first';
   + range-check for mdb_idl_search() result;
lmdb-backend: oomkiller - rename & refine;
lmdb: oomkiller - rename & refine;
oomkick debug
dreamcatcher: refine - detach scopes from lmdb txn-context;