QUIC: registering the compat extension in all SSL contexts

QUIC: registering the compat extension in all SSL contexts

With the OpenSSL compatibility layer, the transport parameters custom
TLS extension used to be registered only in SSL contexts of virtual
servers reachable over QUIC.

The ClientHello callback introduced in 0373fe5d9 (1.29.2) is called
by OpenSSL between collecting and parsing extensions, so the custom
extensions may not match the expected number if the SSL context was
replaced with SSL_set_SSL_CTX().

The fix is to register the extension in all SSL contexts, including
those that cannot be reached over QUIC, so that the array bounds are
preserved; the compatibility layer as a whole is initialized only
if the configuration has QUIC listeners.  The keylog callback,
meaningful for QUIC connections, is kept on QUIC addresses.

Reported by Banny Liao.