Use a single rb_protect in get_vcpus.
Use a single rb_protect in get_vcpus.

By doing it this way, the code is a bit shorter and is also
much easier to read.

Signed-off-by: Chris Lalancette <60b62644009db6b194cc0445b64e9b27bb26433a@redhat.com>

pronix/ruby-libvirt,pronix/ruby-libvirt,pronix/ruby-libvirt