weired, let's reinstall all perl packages...
opkg install --force-reinstall perl perlbase-base perlbase-cgi perlbase-essential perlbase-file perlbase-bytes perlbase-config perlbase-data perlbase-db-file perlbase-digest perlbase-encode perlbase-encoding perlbase-fcntl perlbase-gdbm-file perlbase-integer perlbase-socket perlbase-time perlbase-unicode perlbase-unicore perlbase-utf8 perlbase-xsloader