Autodetect more OpenSSL installation paths (for Mac OS X)

As summarized in http://www.openwall.com/lists/john-users/2016/08/04/3 recent Mac OS X now needs its OpenSSL installed by weird means, and it gets installed in weird places. This makes it tricky to build JtR jumbo. Let's enhance our configure.ac to check for OpenSSL headers and libraries in those directories by default, much like it already does check for headers in /usr/local/ssl now. (We were just reported, privately, of a failed build attempt on Mac OS X where ./configure finds the headers, but not the libraries. I don't know how exactly this happened, but I expect issues and reports of this sort to be frequent unless we look for both of these things in multiple directories that various Mac OS X tools install into by default.)

Start in configure.ac and inspect how the existing /usr/local/ssl header check works, including how library detection is handled. Identify the additional Mac OS X installation locations implied by the issue, then verify with ./configure that OpenSSL headers and libraries are both found there. Done means the reported Mac OS X build path is detected by default.