- Build enable-ec_nistp_64_gcc_128, ecdh is many times faster
but only works in x86_64.
According to the openSSL team
"it is superior to the default in multiple regards (speed, and also
security as the new implementations are secure against timing
attacks)"
It is not enabled by default due to the build system being unable
to detect if the compiler supports __uint128_t. (forwarded request 181467 from elvigia)