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/plugins/gcrypt/gcrypt_dh.h

@@ -32,9 +32,9 @@ typedef struct gcrypt_dh_t gcrypt_dh_t;
 struct gcrypt_dh_t {
 
 	/**
-	 * Implements diffie_hellman_t interface.
+	 * Implements key_exchange_t interface.
 	 */
-	diffie_hellman_t dh;
+	key_exchange_t ke;
 };
 
 /**
@@ -43,7 +43,7 @@ struct gcrypt_dh_t {
  * @param group			Diffie Hellman group number to use
  * @return				gcrypt_dh_t object, NULL if not supported
  */
-gcrypt_dh_t *gcrypt_dh_create(diffie_hellman_group_t group);
+gcrypt_dh_t *gcrypt_dh_create(key_exchange_method_t group);
 
 /**
  * Creates a new gcrypt_dh_t object for MODP_CUSTOM.
@@ -52,7 +52,7 @@ gcrypt_dh_t *gcrypt_dh_create(diffie_hellman_group_t group);
  * @param ...			expects generator and prime as chunk_t
  * @return				gcrypt_dh_t object, NULL if not supported
  */
-gcrypt_dh_t *gcrypt_dh_create_custom(diffie_hellman_group_t group, ...);
+gcrypt_dh_t *gcrypt_dh_create_custom(key_exchange_method_t group, ...);
 
 #endif /** GCRYPT_DH_H_ @}*/