qemu: blockcopy: sanitize permission handling for 'mirror'
qemu: blockcopy: sanitize permission handling for 'mirror'

At the point when we want to modify the permissions for the 'mirror' we
know whether it is supposed to have a backing chain or no. Given that
mirror->backingStore is populated only when we'd need to touch it ayways
we can use qemuDomainStorageSourceChainAccessAllow even in place of
qemuDomainStorageSourceAccessAllow used for other cases to simplify the
code.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

olafhering/libvirt,eskultety/libvirt,andreabolognani/libvirt,zippy2/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jardasgit/libvirt,jardasgit/libvirt,libvirt/libvirt,eskultety/libvirt,jfehlig/libvirt,nertpinx/libvirt,jardasgit/libvirt,zippy2/libvirt,jardasgit/libvirt,crobinso/libvirt,nertpinx/libvirt,jfehlig/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,crobinso/libvirt,eskultety/libvirt,eskultety/libvirt,nertpinx/libvirt,andreabolognani/libvirt,jfehlig/libvirt,zippy2/libvirt,fabianfreyer/libvirt,olafhering/libvirt,nertpinx/libvirt,jardasgit/libvirt,crobinso/libvirt,zippy2/libvirt,andreabolognani/libvirt,eskultety/libvirt,libvirt/libvirt,crobinso/libvirt,olafhering/libvirt