Rename diffie_hellman_t to key_exchange_t and change the interface etc.

This makes it more generic so we can use it for QSKE methods.

src/libstrongswan/crypto/transform.c

@@ -23,7 +23,7 @@ ENUM_BEGIN(transform_type_names, ENCRYPTION_ALGORITHM, EXTENDED_SEQUENCE_NUMBERS
 	"ENCRYPTION_ALGORITHM",
 	"PSEUDO_RANDOM_FUNCTION",
 	"INTEGRITY_ALGORITHM",
-	"DIFFIE_HELLMAN_GROUP",
+	"KEY_EXCHANGE_METHOD",
 	"EXTENDED_SEQUENCE_NUMBERS");
 ENUM_NEXT(transform_type_names, HASH_ALGORITHM, KEY_DERIVATION_FUNCTION,
 		  EXTENDED_SEQUENCE_NUMBERS,
@@ -59,8 +59,8 @@ enum_name_t* transform_get_enum_names(transform_type_t type)
 			return pseudo_random_function_names;
 		case INTEGRITY_ALGORITHM:
 			return integrity_algorithm_names;
-		case DIFFIE_HELLMAN_GROUP:
-			return diffie_hellman_group_names;
+		case KEY_EXCHANGE_METHOD:
+			return key_exchange_method_names;
 		case EXTENDED_SEQUENCE_NUMBERS:
 			return extended_sequence_numbers_names;
 		case EXTENDED_OUTPUT_FUNCTION: