[erlang-patches] Callback attribute for better definition of behaviour callbacks.

[Stavros Aronis]

I've been doing some work related to this patch and I found a small
error. I have fixed it and rebased the whole branch on the current
dev. Should I replace my github copy with the new one?

If not, the new branch is here:

  git fetch git@REDACTED:aronisstav/otp.git callback-attr-new

Thanks in advance!

Stavros Aronis