tp_intset_copy etc.: set #TpIntSet.largest_ever correctly on the copy
tp_intset_copy etc.: set #TpIntSet.largest_ever correctly on the copy

This fixes a regression in which TpIntSetIter terminated too early
(but TpIntSetFastIter was already correct, because it doesn't iterate
in order).

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib