A flock module for Windows9x and other systems lacking
a good perl flock() function (not platform specific)

Rationale: flock on Win95/98 is badly broken but
perl code needs to be portable. In addition, sometimes code written
to use flock() on one workstation needs to be ported to running on
several networked servers and clients. One way to allow this is
to override perl's open(), flock(), and close(). We then get an
absolute file specification for all opened files and and use it in
a hash to create a unique lock for the file using the File::LockDir
module from the "Perl Cookbook", by Christiansen and Torkington
(O'Reilly, 1998). This module may be included in the CPAN
distribution but belongs to those authors. New code has been
kept to a minimum.
