Remove support for MD2

No part of IKE/IPsec or X.509 uses MD2 anymore, so there really is no
reason to still support it (unlike MD4 that is used in EAP-MSCHAPv2,
MD5 that's used in EAP-MD5, or SHA-1 that's used for e.g. NAT-D hashes).

It caused test vectors to fail on systems where OpenSSL is built with
MD2 support but has it disabled at runtime.

src/libstrongswan/credentials/containers/pkcs12.c

@@ -83,7 +83,6 @@ static bool derive_key(hash_algorithm_t hash, chunk_t unicode, chunk_t salt,
 	}
 	switch (hash)
 	{
-		case HASH_MD2:
 		case HASH_MD5:
 		case HASH_SHA1:
 		case HASH_SHA224: