wolfssl: Support wolfSSL builds missing TLS 1.1

wolfssl: Support wolfSSL builds missing TLS 1.1

The wolfSSL TLS library defines NO_OLD_TLS in some of their build
configurations and that causes the library to be built without TLS 1.1.
For example if MD5 is explicitly disabled when building wolfSSL then
that defines NO_OLD_TLS and the library is built without TLS 1.1 [1].

Prior to this change attempting to build curl with a wolfSSL that was
built with NO_OLD_TLS would cause a build link error undefined reference
to wolfTLSv1_client_method.

[1]: https://github.com/wolfSSL/wolfssl/blob/v4.5.0-stable/configure.ac#L2366

Bug: https://curl.se/mail/lib-2020-12/0121.html
Reported-by: Julian Montes
Closes https://github.com/curl/curl/pull/6388