devel/libchdr: New port: Standalone library for reading MAME CHDv1-v5 formats

libchdr is a standalone library for reading MAME's CHDv1-v5 formats.

The code is based off of MAME's old C codebase which read up to CHDv4 with
OS-dependent features removed, and CHDv5 support backported from MAME's current
C++ codebase.

WWW: https://github.com/rtissera/libchdr

PR: 282692