/usr/include/libreoffice/rtl/ is in libreoffice-dev-common 1:6.0.3-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libreoffice/rtl/alloc.h
/usr/include/libreoffice/rtl/bootstrap.h
/usr/include/libreoffice/rtl/bootstrap.hxx
/usr/include/libreoffice/rtl/byteseq.h
/usr/include/libreoffice/rtl/byteseq.hxx
/usr/include/libreoffice/rtl/character.hxx
/usr/include/libreoffice/rtl/cipher.h
/usr/include/libreoffice/rtl/crc.h
/usr/include/libreoffice/rtl/digest.h
/usr/include/libreoffice/rtl/instance.hxx
/usr/include/libreoffice/rtl/locale.h
/usr/include/libreoffice/rtl/malformeduriexception.hxx
/usr/include/libreoffice/rtl/math.h
/usr/include/libreoffice/rtl/math.hxx
/usr/include/libreoffice/rtl/process.h
/usr/include/libreoffice/rtl/random.h
/usr/include/libreoffice/rtl/ref.hxx
/usr/include/libreoffice/rtl/strbuf.h
/usr/include/libreoffice/rtl/strbuf.hxx
/usr/include/libreoffice/rtl/string.h
/usr/include/libreoffice/rtl/string.hxx
/usr/include/libreoffice/rtl/stringconcat.hxx
/usr/include/libreoffice/rtl/stringutils.hxx
/usr/include/libreoffice/rtl/tencinfo.h
/usr/include/libreoffice/rtl/textcvt.h
/usr/include/libreoffice/rtl/textenc.h
/usr/include/libreoffice/rtl/unload.h
/usr/include/libreoffice/rtl/uri.h
/usr/include/libreoffice/rtl/uri.hxx
/usr/include/libreoffice/rtl/ustrbuf.h
/usr/include/libreoffice/rtl/ustrbuf.hxx
/usr/include/libreoffice/rtl/ustring.h
/usr/include/libreoffice/rtl/ustring.hxx
/usr/include/libreoffice/rtl/uuid.h