devel/libmt32emu: New port: Emulate Roland MT-32, CM-32L and LAPC-I synthesiser modules

mt32emu is part of the Munt project. It represents a C/C++ library named
libmt32emu which allows to emulate (approximately) the Roland MT-32, CM-32L and
LAPC-I synthesiser modules.

WWW: https://munt.sourceforge.net

PR: 284634
Co-authored-by: Max Brazhnikov <makc@FreeBSD.org>