Use g_steal_pointer where possible

Use g_steal_pointer where possible

Via coccinelle (not the handbag!)
spatches used:
@ rule1 @
identifier a, b;
symbol NULL;
@@

- b = a;
  ... when != a
- a = NULL;
+ b = g_steal_pointer(&a);

@@

- *b = a;
  ... when != a
- a = NULL;
+ *b = g_steal_pointer(&a);

Signed-off-by: Kristina Hanicova <khanicov@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>