Long ago in commit dfa1e1dd the scheduler weight was accidentally
hardcoded to 1000. Weight is a setting with no unit since it is
relative to the weight of other domains. If no weight is specified,
libxl defaults to 256.

Instead of hardcoding the weight to 1000, honor any <shares> specified
in <cputune>. libvirt's notion of shares is synonomous to libxl's
scheduler weight setting. If shares is unspecified, defer default
weight setting to libxl.

Removing the hardcoded weight required some test fixup. While at it,
add an explicit test for <shares> conversion to scheduler weight.
Signed-off-by: NJim Fehlig <jfehlig@suse.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>