Merge branch 'openssl-providers'

Optionally load the legacy provider in OpenSSL 3 (enabled, by default) to
make algorithms like MD4 and DES available, which we require for
EAP-MSCHAPv2.  Allow explicitly loading the fips provider via existing
fips_mode option.  The loaded providers, whether influenced by the above
options or not, are logged.

Closes strongswan/strongswan#759