Add contains() function that checks if an item is in an idxset. Add
isdisjoint(), issubset(), issuperset() and equals() functions that
element-wise compare two idxsets.
Add complementary functions to the existing idxset search(), first(),
next() functions that work in the reverse direction: reverse_search(),
last() and previous().
Add steal_last() to remove and return the last item in the idxset.
[Alper: original patches for PulseAudio, split from other commit]
Co-developed-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Link: fb63e58931
Link: ec668ac44b
Link: 97d9c28579
236b7ee0e2