OpenSSL: Fix forcing SSLv3 connections

Since ad34a2d5c87c7f4b14e8dded3 (present in 7.34.0 release) forcing
SSLv3 will always return the error "curl: (35) Unsupported SSL protocol
version" Can be replicated with `curl -I -3 https://www.google.com/`.
This fix simply allows for v3 to be forced.