CA-1623: Update Pool.join/eject
CA-1623: Update Pool.join/eject

Pool.join is now allowed when CPU features and vendor are identical, while other CPU details need not be the same.
Pool.eject clears all CPU feature masks.

Signed-off-by: Rob Hoes <8783b3376fb07d39edffc8d7da68a6de3874a7e6@citrix.com>

koushikcgit/xcp-networkd,djs55/xcp-networkd,djs55/xcp-networkd,sharady/xcp-networkd,robhoes/squeezed,koushikcgit/xcp-rrdd,koushikcgit/xcp-networkd,johnelse/xcp-rrdd,sharady/xcp-networkd,djs55/squeezed,djs55/xcp-rrdd,johnelse/xcp-rrdd,simonjbeaumont/xcp-rrdd,koushikcgit/xcp-rrdd,koushikcgit/xcp-rrdd,simonjbeaumont/xcp-rrdd,djs55/xcp-rrdd