/usr/include/ is in libmpd-dev 0.20.0-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libmpd-1.0/
/usr/include/libmpd-1.0/libmpd/
/usr/include/libmpd-1.0/libmpd/debug_printf.h
/usr/include/libmpd-1.0/libmpd/libmpd-database.h
/usr/include/libmpd-1.0/libmpd/libmpd-internal.h
/usr/include/libmpd-1.0/libmpd/libmpd-player.h
/usr/include/libmpd-1.0/libmpd/libmpd-playlist.h
/usr/include/libmpd-1.0/libmpd/libmpd-status.h
/usr/include/libmpd-1.0/libmpd/libmpd-sticker.h
/usr/include/libmpd-1.0/libmpd/libmpd-strfsong.h
/usr/include/libmpd-1.0/libmpd/libmpd-version.h
/usr/include/libmpd-1.0/libmpd/libmpd.h
/usr/include/libmpd-1.0/libmpd/libmpdclient.h