* db/hash/ndbm.c: Change all uses of `errno' struct member to `errnum'.
(dbm_open): Use dynamic allocation for file name buffer, instead of
limitting its size to MAXPATHLEN.
* db/btree/bt_open.c (tmp): Use dynamic allocation for file name
buffer, instead of limitting its size to MAXPATHLEN.
* db/hash/hash.h (HTAB): Rename member `errno' to `errnum'.
* db/hash/hash.c: Change all uses of `errno' struct member to `errnum'.