Avoid errors with a priori inapplicable protocol bounds

Avoid errors with a priori inapplicable protocol bounds

The 'MinProtocol' and 'MaxProtocol' configuration commands now silently
ignore TLS protocol version bounds when configurign DTLS-based contexts,
and conversely, silently ignore DTLS protocol version bounds when
configuring TLS-based contexts.  The commands can be repeated to set
bounds of both types.  The same applies with the corresponding
"min_protocol" and "max_protocol" command-line switches, in case some
application uses both TLS and DTLS.

SSL_CTX instances that are created for a fixed protocol version (e.g.
TLSv1_server_method()) also silently ignore version bounds.  Previously
attempts to apply bounds to these protocol versions would result in an
error.  Now only the "version-flexible" SSL_CTX instances are subject to
limits in configuration files in command-line options.

Expected to resolve #12394

Reviewed-by: Paul Dale <paul.dale@oracle.com>
GH: #12472