/usr/include/x86_64-linux-gnu/ is in libwinpr-dev 1.1.0~git20140921.1.440916e+dfsg1-13+deb9u3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/x86_64-linux-gnu/winpr/
/usr/include/x86_64-linux-gnu/winpr/asn1.h
/usr/include/x86_64-linux-gnu/winpr/bcrypt.h
/usr/include/x86_64-linux-gnu/winpr/cmdline.h
/usr/include/x86_64-linux-gnu/winpr/collections.h
/usr/include/x86_64-linux-gnu/winpr/credentials.h
/usr/include/x86_64-linux-gnu/winpr/credui.h
/usr/include/x86_64-linux-gnu/winpr/crt.h
/usr/include/x86_64-linux-gnu/winpr/crypto.h
/usr/include/x86_64-linux-gnu/winpr/dsparse.h
/usr/include/x86_64-linux-gnu/winpr/endian.h
/usr/include/x86_64-linux-gnu/winpr/environment.h
/usr/include/x86_64-linux-gnu/winpr/error.h
/usr/include/x86_64-linux-gnu/winpr/file.h
/usr/include/x86_64-linux-gnu/winpr/handle.h
/usr/include/x86_64-linux-gnu/winpr/heap.h
/usr/include/x86_64-linux-gnu/winpr/input.h
/usr/include/x86_64-linux-gnu/winpr/interlocked.h
/usr/include/x86_64-linux-gnu/winpr/io.h
/usr/include/x86_64-linux-gnu/winpr/library.h
/usr/include/x86_64-linux-gnu/winpr/memory.h
/usr/include/x86_64-linux-gnu/winpr/midl.h
/usr/include/x86_64-linux-gnu/winpr/ndr.h
/usr/include/x86_64-linux-gnu/winpr/nt.h
/usr/include/x86_64-linux-gnu/winpr/ntlm.h
/usr/include/x86_64-linux-gnu/winpr/path.h
/usr/include/x86_64-linux-gnu/winpr/pipe.h
/usr/include/x86_64-linux-gnu/winpr/platform.h
/usr/include/x86_64-linux-gnu/winpr/pool.h
/usr/include/x86_64-linux-gnu/winpr/print.h
/usr/include/x86_64-linux-gnu/winpr/registry.h
/usr/include/x86_64-linux-gnu/winpr/rpc.h
/usr/include/x86_64-linux-gnu/winpr/sam.h
/usr/include/x86_64-linux-gnu/winpr/schannel.h
/usr/include/x86_64-linux-gnu/winpr/security.h
/usr/include/x86_64-linux-gnu/winpr/spec.h
/usr/include/x86_64-linux-gnu/winpr/sspi.h
/usr/include/x86_64-linux-gnu/winpr/sspicli.h
/usr/include/x86_64-linux-gnu/winpr/stream.h
/usr/include/x86_64-linux-gnu/winpr/string.h
/usr/include/x86_64-linux-gnu/winpr/synch.h
/usr/include/x86_64-linux-gnu/winpr/sysinfo.h
/usr/include/x86_64-linux-gnu/winpr/tchar.h
/usr/include/x86_64-linux-gnu/winpr/thread.h
/usr/include/x86_64-linux-gnu/winpr/timezone.h
/usr/include/x86_64-linux-gnu/winpr/windows.h
/usr/include/x86_64-linux-gnu/winpr/winhttp.h
/usr/include/x86_64-linux-gnu/winpr/winpr.h
/usr/include/x86_64-linux-gnu/winpr/winsock.h
/usr/include/x86_64-linux-gnu/winpr/wtypes.h