build: drop libvirt setuid library build

build: drop libvirt setuid library build

The virt-login-shell setuid program is now a tiny piece of code
that only uses standard libc functions, and santizes the execution
environment before invoking the real virt-login-shell-helper.
The latter is thus able to use the normal libvirt.so build,
allowing us to delete the special cut down setuid library build.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>