openssl: Load "legacy" provider in OpenSSL 3 for algorithms like MD4, DES etc.

openssl: Load "legacy" provider in OpenSSL 3 for algorithms like MD4, DES etc.

We still require these algorithms for e.g. EAP-MSCHAPv2, so the option is
enabled, by default.  To use other providers (e.g. fips or even custom
ones), the option can be disabled and the providers to load/activate can
be configured in openssl.cnf.  For instance, the following has the same
effect as enabling the option:

    openssl_conf = openssl_init

    [openssl_init]
    providers = providers

    [providers]
    default = activate
    legacy = activate

    [activate]
    activate = yes