SA_SIGINFO | SA_RESETHAND fix backport

[Fedor Indutny]

Hello people!

While trying to fix node.js/io.js issue with signal handling
on FreeBSD 10.1, I have found that the problem was due to a kernel
bug. Luckily that bug is fixed in:

https://github.com/freebsd/freebsd/commit/4501dadd00cece6d06392c42e5fc6af07731e451

But it looks like the fix wasn't backported to 10.x .

Do you think it might be possible to do it? I'd really appreciate
this.

Thank you,
Fedor.