I cannot install Crypt::SSLeay on a modern Ubuntu due to this bug: https://rt.cpan.org/Public/Bug/Display.html?id=116663
However it's not necessary for WebService::Rackspace::CloudFiles to list Crypt::SSLeay as a dependency. LWP::Protocol::https is already listed as a dependency, which appears to be enough, as per:
https://metacpan.org/pod/Crypt::SSLeay#DO-YOU-NEED-Crypt::SSLeay?
My workaround:
Remove requires 'Crypt::SSLeay' => '0'; from Makefile.PL, then continue install.