ab: Add option --with-ssl-patch

I don't know if this is of interest to a lot of people, but since I needed this option today to test an SSL-enabled nginx website, I'm pushing this out in case it meets the standards of acceptable patches to homebrew-dupes.

With `--with-ssl-patch` specified, ab will now be built with [a patch](https://issues.apache.org/bugzilla/attachment.cgi?id=28435&action=edit) for [Bug 49382 - ab says "SSL read failed"](https://issues.apache.org/bugzilla/show_bug.cgi?id=49382) applied.