support older gcrypt libraries not defining the CAMELLIA cipher

configure.in

@@ -1015,6 +1015,13 @@ fi
 
 if test x$gcrypt = xtrue; then
 	AM_PATH_LIBGCRYPT(,,[AC_MSG_ERROR([libgcrypt not found!])])
+	AC_MSG_CHECKING([gcrypt CAMELLIA cipher])
+	AC_TRY_COMPILE(
+		[#include <gcrypt.h>],
+		[enum gcry_cipher_algos alg = GCRY_CIPHER_CAMELLIA128;],
+		[AC_MSG_RESULT([yes]); AC_DEFINE([HAVE_GCRY_CIPHER_CAMELLIA])],
+		[AC_MSG_RESULT([no])]
+	)
 fi
 
 if test x$uci = xtrue; then

src/libstrongswan/plugins/gcrypt/gcrypt_crypter.c

@@ -180,6 +180,7 @@ gcrypt_crypter_t *gcrypt_crypter_create(encryption_algorithm_t algo,
 		case ENCR_CAMELLIA_CBC:
 			switch (key_size)
 			{
+#ifdef HAVE_GCRY_CIPHER_CAMELLIA
 				case 16:
 					gcrypt_alg = GCRY_CIPHER_CAMELLIA128;
 					break;
@@ -189,6 +190,7 @@ gcrypt_crypter_t *gcrypt_crypter_create(encryption_algorithm_t algo,
 				case 32:
 					gcrypt_alg = GCRY_CIPHER_CAMELLIA256;
 					break;
+#endif /* HAVE_GCRY_CIPHER_CAMELLIA */
 				default:
 					return NULL;
 			}