add cpu-shares to ctr

This allows the cpu shares to be modified via ctr.

Signed-off-by: Michael Crosby <michael@thepasture.io>

oci/spec_opts_nonlinux.go

@@ -36,3 +36,11 @@ var WithAllCurrentCapabilities = func(ctx context.Context, client Client, c *con
 var WithAllKnownCapabilities = func(ctx context.Context, client Client, c *containers.Container, s *Spec) error {
 	return WithCapabilities(nil)(ctx, client, c, s)
 }
+
+// WithCPUShares sets the container's cpu shares
+//nolint: deadcode, unused
+func WithCPUShares(shares uint64) SpecOpts {
+	return func(ctx context.Context, _ Client, c *containers.Container, s *Spec) error {
+		return nil
+	}
+}