/usr/lib/x86_64-linux-gnu/ is in liballegro5-dev 2:5.2.2-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/allegro-5.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/allegro_color-5.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/allegro_font-5.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/allegro_main-5.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/allegro_memfile-5.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/allegro_primitives-5.pc
/usr/lib/x86_64-linux-gnu/liballegro.so
/usr/lib/x86_64-linux-gnu/liballegro_color.so
/usr/lib/x86_64-linux-gnu/liballegro_font.so
/usr/lib/x86_64-linux-gnu/liballegro_main.so
/usr/lib/x86_64-linux-gnu/liballegro_memfile.so
/usr/lib/x86_64-linux-gnu/liballegro_primitives.so