Add support for testing supported curves

since early versions of 1.0.2 openssl supports -curves command line
option, it allows us to set the curves advertised as supported

use the same approach to testing: advertise all, check what server
accepts, remove the accepted from list, repeat. When server aborts
connection or selects non ECC cipher, we know that we've tested all.
I really really want curves testing. And I'm super excited about your patch, but we need to find a better way to list available curves because maintaining a static list is not an option.
We're all busy with tons of projects, and 3 years from now, this list will be outdated for sure. I want to be able to bring cipherscan up to date by only upgrading the openssl binary, and not have to modify code.

Isn't there a way to programmatically get the list of curves openssl supports? sed/awk is fine too.