/usr/include/dclib-0.3/dclib/core/ is in libdc-dev 0.3.24~svn3121-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/dclib-0.3/dclib/core/casyncdns.h
/usr/include/dclib-0.3/dclib/core/cbase32.h
/usr/include/dclib-0.3/dclib/core/cbase64.h
/usr/include/dclib-0.3/dclib/core/cbytearray.h
/usr/include/dclib-0.3/dclib/core/cbz.h
/usr/include/dclib-0.3/dclib/core/ccallback.h
/usr/include/dclib-0.3/dclib/core/cconnection.h
/usr/include/dclib-0.3/dclib/core/cdir.h
/usr/include/dclib-0.3/dclib/core/cfile.h
/usr/include/dclib-0.3/dclib/core/che3.h
/usr/include/dclib-0.3/dclib/core/ciconv.h
/usr/include/dclib-0.3/dclib/core/clist.h
/usr/include/dclib-0.3/dclib/core/clisten.h
/usr/include/dclib-0.3/dclib/core/clogfile.h
/usr/include/dclib-0.3/dclib/core/cmanager.h
/usr/include/dclib-0.3/dclib/core/cmutex.h
/usr/include/dclib-0.3/dclib/core/cnetaddr.h
/usr/include/dclib-0.3/dclib/core/cplugin.h
/usr/include/dclib-0.3/dclib/core/csingleton.h
/usr/include/dclib-0.3/dclib/core/csocket.h
/usr/include/dclib-0.3/dclib/core/cssl.h
/usr/include/dclib-0.3/dclib/core/cstring.h
/usr/include/dclib-0.3/dclib/core/cstringhash.h
/usr/include/dclib-0.3/dclib/core/cstringlist.h
/usr/include/dclib-0.3/dclib/core/cthread.h
/usr/include/dclib-0.3/dclib/core/ctraffic.h
/usr/include/dclib-0.3/dclib/core/cxml.h
/usr/include/dclib-0.3/dclib/core/czlib.h
/usr/include/dclib-0.3/dclib/core/platform.h
/usr/include/dclib-0.3/dclib/core/types.h