FTOK() collisions

[WiredTombstone]

ftok() can have collisions quite easily especially on systems with lots of files. Users of the shared memory class may want to specify a temporary file so that memory is only shared between specific groups of executing processes. Using a file's inode is a much better way to prevent collisions of this nature.

[maksimovic]

It's been years ago since you've opened this PR, but feel free to open it over here at https://github.com/maksimovic/simple-fork-php

I needed this to be compatible with PHP 7.2+ (8 included) and eventually had it released as a separate package.