Revert disabling SSH agent by default

!60 (merged) disabled building the SSH agent by default.

I tried doing that when preparing the Debian update but I had the same issue reported at https://bugzilla.redhat.com/show_bug.cgi?id=2250704 .

It's my understanding that this change was motivated by a Fedora initiative but if even Fedora sees this change as not working, maybe the change should be reverted.