[erlang-patches] better delete_any in gb_{sets, trees}, better difference in gb_sets

[Francesco Mazzoli]

OK, sorry if it took me so long (I'm on a different email but I'm
still the same :).

I've modified the code in `gb_delete_any' according to the comments,
I'll look at the other branch soon:
https://github.com/bitonic/otp/compare/master...gb_delete_any.

I had some objections regarding the comments on GitHub, but now they
seem to be down - that's why we shouldn't use systems like GitHub to
communicate.

Since the other comments are down as well, I'm not sure how to proceed
for the other branch. Do you still have a copy, or could you rewrite
the here? Thanks.

Francesco.