[NEW-PORT] devel/talloc242: Hierarchical pool based memory allocator

[kiwi]

Summary

devel/talloc242: Hierarchical pool based memory allocator

A hierarchical pool based memory allocator with destructors. It uses
reference counting to determine when memory should be freed.

This port is needed for Samba 4.20

Sponsored by:   Klara, Inc.
Approved by:    0mp (mentor)

Test Plan

This port is needed for samba 4.20. Tested with poudriere and build of samba4.20

[diizzy]

Subject and desc are incorrect, refers to talloc instead of libtevent