qemu: remove use of the terms 'master' and 'slave' when iterating CPUs
qemu: remove use of the terms 'master' and 'slave' when iterating CPUs

When querying QEMU we have to iterate over two nested sets
of CPUs. The terms "main vcpu" and "sub vcpu" are a good
representation.

Reviewed-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

nertpinx/libvirt,zippy2/libvirt,jardasgit/libvirt,nertpinx/libvirt,zippy2/libvirt,olafhering/libvirt,nertpinx/libvirt,jfehlig/libvirt,nertpinx/libvirt,libvirt/libvirt,jardasgit/libvirt,jardasgit/libvirt,zippy2/libvirt,crobinso/libvirt,zippy2/libvirt,jfehlig/libvirt,libvirt/libvirt,olafhering/libvirt,olafhering/libvirt,libvirt/libvirt,jardasgit/libvirt,crobinso/libvirt,jardasgit/libvirt,nertpinx/libvirt,olafhering/libvirt,jfehlig/libvirt,jfehlig/libvirt,crobinso/libvirt,crobinso/libvirt,libvirt/libvirt