prevent git ref/unref mismatches. prevent reference promotion to owner

prevent git ref/unref mismatches. prevent reference promotion to owner

If talloc_steal occurs on an allocation that had references but whose
owner died before the steal, then one less unref must be done.

This is very weird.

These fixes seperate ownership and referencing internally to talloc

Signed-off-by: Sam Liddicott <sam@liddicott.com>