Remove HASH_PREFERRED, usages are replaced with HASH_SHA1, which is required for IKEv2 anyway

src/libstrongswan/crypto/hashers/hasher.h

@@ -37,16 +37,14 @@ typedef struct hasher_t hasher_t;
 enum hash_algorithm_t {
 	/** not specified hash function */
 	HASH_UNKNOWN 		= 0,
-	/** preferred hash function, general purpose */
-	HASH_PREFERRED		= 1,
-	HASH_MD2 			= 2,
-	HASH_MD4			= 3,
-	HASH_MD5 			= 4,
-	HASH_SHA1 			= 5,
-	HASH_SHA224			= 6,
-	HASH_SHA256 		= 7,
-	HASH_SHA384 		= 8,
-	HASH_SHA512 		= 9
+	HASH_MD2 			= 1,
+	HASH_MD4			= 2,
+	HASH_MD5 			= 3,
+	HASH_SHA1 			= 4,
+	HASH_SHA224			= 5,
+	HASH_SHA256 		= 6,
+	HASH_SHA384 		= 7,
+	HASH_SHA512 		= 8
 };
 
 #define HASH_SIZE_MD2		16