CSocket Fail-to-Build with Debian Unstable OpenSSL - No SSLv3 Support

[teward]

This is currently observed in Debian, but may be visible elsewhere. Currently, OpenSSL is in the process of transitioning in Debian to drop SSLv3 completely. In the current ZNC 1.6.1 in Debian, the package fails to build as a result of SSLv3 symbols not being defined. I can replicate this with a Debian Unstable VM, myself.

This is observed here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=804618 and the relevant build failures are below:

src/Csocket.cpp: In member function ‘virtual bool Csock::SSLClientSetup()’:
src/Csocket.cpp:1467:48: error: ‘SSLv3_client_method’ was not declared in this scope
m_ssl_ctx = SSL_CTX_new( SSLv3_client_method() );
^
src/Csocket.cpp: In member function ‘SSL_CTX* Csock::SetupServerCTX()’:
src/Csocket.cpp:1589:43: error: ‘SSLv3_server_method’ was not declared in this scope
pCTX = SSL_CTX_new( SSLv3_server_method() );
^
Makefile:116: recipe for target 'src/Csocket.o' failed
make[2]: *** [src/Csocket.o] Error 1
make[2]: Leaving directory '/znc-1.6.1'

Given that this is not defined, anymore, there will be Fail to Builds with OpenSSL in Debian going forward into the future.

[teward]

Doh, searched 'sslv3' got nothing, this is a dupe of #1146