/usr/include/msgpack/predef/architecture/ is in libmsgpack-dev 1.4.2-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/msgpack/predef/architecture/alpha.h
/usr/include/msgpack/predef/architecture/arm.h
/usr/include/msgpack/predef/architecture/blackfin.h
/usr/include/msgpack/predef/architecture/convex.h
/usr/include/msgpack/predef/architecture/ia64.h
/usr/include/msgpack/predef/architecture/m68k.h
/usr/include/msgpack/predef/architecture/mips.h
/usr/include/msgpack/predef/architecture/parisc.h
/usr/include/msgpack/predef/architecture/ppc.h
/usr/include/msgpack/predef/architecture/pyramid.h
/usr/include/msgpack/predef/architecture/rs6k.h
/usr/include/msgpack/predef/architecture/sparc.h
/usr/include/msgpack/predef/architecture/superh.h
/usr/include/msgpack/predef/architecture/sys370.h
/usr/include/msgpack/predef/architecture/sys390.h
/usr/include/msgpack/predef/architecture/x86/
/usr/include/msgpack/predef/architecture/x86.h
/usr/include/msgpack/predef/architecture/x86/32.h
/usr/include/msgpack/predef/architecture/x86/64.h
/usr/include/msgpack/predef/architecture/z.h