libwebsockets

opensslv3: handle deprecation of EC apis

openssl v3-alpha11 has marked EC_KEY pieces as deprecated... we use it in
LWS_WITH_GENCRYPTO but the related RSA etc pieces were already deprecated
for that.  We use EC_KEY pieces in vhost init...

The apis are not removed but deprecated, we should have a way to keep
trucking, but as it is the deprecation warning is promoted to an error.

Let's add LWS_SUPPRESS_DEPRECATED_API_WARNINGS option off by default.  If
enabled at cmake, external deprecated api warnings are suppressed.  This
gives a general workaround for now for opensslv3.

In addition, even if you don't do that, let's notice we are on openssl v3
and don't build the EC curve selection stuff, I don't think anyone is
actually using it anyway.