ssl_filter: make is_ssl_error() "pure", not "const"
ssl_filter: make is_ssl_error() "pure", not "const"

The return value depends on attributes inside the SSL object.

CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy