Add openssl_prefix to Configure and friends

[craigberry]

In order to add TLS to the core, we need a library, and OpenSSL is as ubiquitous as it gets. So detect where it is with logic borrowed from Net::SSLeay.

[jkeenan]

I configured with blead and with your branch on each of Ubuntu Linux 24.04 LTS and OpenBSD-6.9. I then examined the content of config.sh in blead and branch on both platforms. In both cases the difference (ignoring lines for Configuration time and cf_time) was:

982a983
> openssl_prefix='/usr'

Is that what you would expect?

[craigberry]

I configured with blead and with your branch on each of Ubuntu Linux 24.04 LTS and OpenBSD-6.9. I then examined the content of config.sh in blead and branch on both platforms. In both cases the difference (ignoring lines for Configuration time and cf_time) was:

982a983
> openssl_prefix='/usr'

Is that what you would expect?

Thanks for testing. That looks like what I'd expect. The logic I'm replicating is from the Net::SSLeay Makefile.PL here. On most unixy platforms you should be able to do which openssl and chop off /bin/openssl from the end and what's left will be your prefix.

[Leont]

Shouldn't this start with $libpth/$libspath

[craigberry]

That's a good question. I don't really have the data to know the answer for sure, having just lifted the candidate locations straight from the Net::SSLeay Makefile.PL. But keeping it simple and using infrastructure we already have are good things to do, so maybe I'll switch to iterating through $libpth. If it misses something weird, people can always add hints or make adjustments as needed later.

[craigberry]

Now starts from $libpth.