Is perl actually a symlink to microperl? I seem to remember this being the case with wrt, and at a glance it looks like this is still the case. Various embedded system ship with mini/microperl and do this. strict has been core since perl 5. Mini/microperl are cut down, not full perl distros. If you are using a packing system you likely need to install the package which includes strict (a quick web search suggests perlbase/github link) which they do list as a dependency in their WWW::Mechanize package. This may be an issue with the package manager you used, or the packages themselves. If concerned replicate the problem, using the package manager in verbose or logging mode and discuss with the openwrt people?