- Revert to the legacy TLS 1.2 key logging code for LibreSSL.
- Document SSLKEYLOGFILE for LibreSSL is TLS 1.2 max.
Prior to this change if the user specified a filename in the
SSLKEYLOGFILE environment variable and was using LibreSSL 3.5.0+ then
an empty file would be created and no keys would be logged.
This is effectively a revert of e43474b4 which changed openssl.c to use
SSL_CTX_set_keylog_callback for LibreSSL 3.5.0+. Unfortunately LibreSSL
added that function only as a stub that doesn't actually do anything.
Reported-by: Gonçalo Carvalho
Fixes https://github.com/curl/curl/issues/13672
Closes https://github.com/curl/curl/pull/13682
9aae9bf817