/usr/lib/x86_64-linux-gnu/ is in libcyrus-imap-perl 2.5.10-3ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/perl5/
/usr/lib/x86_64-linux-gnu/perl5/5.26/
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/IMAP/
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/IMAP/Admin.pm
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/IMAP/IMSP.pm
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/IMAP/Shell.pm
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/IMAP.pm
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/SIEVE/
/usr/lib/x86_64-linux-gnu/perl5/5.26/Cyrus/SIEVE/managesieve.pm
/usr/lib/x86_64-linux-gnu/perl5/5.26/auto/
/usr/lib/x86_64-linux-gnu/perl5/5.26/auto/Cyrus/
/usr/lib/x86_64-linux-gnu/perl5/5.26/auto/Cyrus/IMAP/
/usr/lib/x86_64-linux-gnu/perl5/5.26/auto/Cyrus/IMAP/IMAP.so
/usr/lib/x86_64-linux-gnu/perl5/5.26/auto/Cyrus/SIEVE/
/usr/lib/x86_64-linux-gnu/perl5/5.26/auto/Cyrus/SIEVE/managesieve/
/usr/lib/x86_64-linux-gnu/perl5/5.26/auto/Cyrus/SIEVE/managesieve/managesieve.so