VG::add_pv: Implement recursive dep loop search and check for VG membership
VG::add_pv: Implement recursive dep loop search and check for VG membership

Don't allow a PV to be added that is on an LV that leads back to us.

Don't allow a PV to be added that already has metadata. I'm not sure if
this is the right test, but it's a start.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

agrover/melvin