erdtls: Only use SSL_CTX_set_ecdh_auto() when using openssl >= 1.0.2
erdtls: Only use SSL_CTX_set_ecdh_auto() when using openssl >= 1.0.2

Linux distributions still have 1.0.1 usually, and updating to >= 1.0.2 will
require rebuilding and/or porting most applications because of API/ABI
changes.

shelsonjava/openwebrtc-gst-plugins,shelsonjava/openwebrtc-gst-plugins,shelsonjava/openwebrtc-gst-plugins,shelsonjava/openwebrtc-gst-plugins