/usr/share/boinc-dev/lib/ is in libboinc-app-dev 7.9.3+dfsg-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/boinc-dev/lib/app_ipc.h
/usr/share/boinc-dev/lib/boinc_win.h
/usr/share/boinc-dev/lib/common_defs.h
/usr/share/boinc-dev/lib/coproc.h
/usr/share/boinc-dev/lib/crypt.h
/usr/share/boinc-dev/lib/diagnostics.h
/usr/share/boinc-dev/lib/error_numbers.h
/usr/share/boinc-dev/lib/filesys.h
/usr/share/boinc-dev/lib/gui_rpc_client.h
/usr/share/boinc-dev/lib/hostinfo.h
/usr/share/boinc-dev/lib/md5_file.h
/usr/share/boinc-dev/lib/mfile.h
/usr/share/boinc-dev/lib/miofile.h
/usr/share/boinc-dev/lib/msg_log.h
/usr/share/boinc-dev/lib/parse.h
/usr/share/boinc-dev/lib/prefs.h
/usr/share/boinc-dev/lib/proxy_info.h
/usr/share/boinc-dev/lib/str_util.h
/usr/share/boinc-dev/lib/util.h