This is convenience macro, use it more. This commit was generated
using the following spatch:

  @@
  symbol node;
  identifier old;
  identifier ctxt;
  type xmlNodePtr;
  @@
  - xmlNodePtr old;
  + VIR_XPATH_NODE_AUTORESTORE(ctxt);
    ...
  - old = ctxt->node;
    ... when != old
  - ctxt->node = old;

  @@
  symbol node;
  identifier old;
  identifier ctxt;
  type xmlNodePtr;
  @@
  - xmlNodePtr old = ctxt->node;
  + VIR_XPATH_NODE_AUTORESTORE(ctxt);
    ... when != old
  - ctxt->node = old;
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>