Comment 2 for bug 1296215

You appear to have overwritten your system's /usr/bin/perl with a locally-compiled version with a different module path, and now it can't find any of the required system modules. This is not a bug in man-db nor in any of the other programs broken by this. You need to reinstall the system's version of Perl (perhaps "sudo apt-get --reinstall install perl-base perl-modules perl" will help get you started, although there may be other problems), and in future make sure to put locally-built versions of Perl somewhere else.