ndbm support

[Tom Samplonius <tom@uniserve.com>]

  It seems that the owner_ndbm() and modp_ndbm() functions in ndbm.c have 
been modified not to use dbm_pagfno() (I believe in 2.99.26) to get the file 
descriptor associated with the database, but instead to use stat() calls on the 
filename.

  However, the code appears to assume that the database name will equal 
the filename.  This won't work with the original ndbm as separate 
<database name>.dir and <database name>.pag files are used.  This 
won't work with the BSD db package as the a <database name>.db file is 
used.  I guess this will only work with gdbm() as uses only one file, and 
no suffix?

Tom