The @con type security_context_t is actually a "char *", so the
correct check should be to dereference one more level; otherwise,
we could return/use the NULL pointer later in a subsequent
virSecuritySELinuxSetFileconImpl call (using @fcon).
Suggested-by: Michal Prívozník <mprivozn@redhat.com> Signed-off-by: John Ferlan <jferlan@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>