Move FFDH helper functions and macros to more suitable locations

Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
diff --git a/programs/ssl/ssl_test_lib.h b/programs/ssl/ssl_test_lib.h
index 020fc2d..5f9dbdd 100644
--- a/programs/ssl/ssl_test_lib.h
+++ b/programs/ssl/ssl_test_lib.h
@@ -307,5 +307,9 @@
 
 #endif /* !MBEDTLS_TEST_HOOKS */
 
+/* Helper functions for FFDH groups. */
+uint16_t mbedtls_ssl_ffdh_group_from_name(const char *name);
+uint16_t *mbedtls_ssl_ffdh_supported_groups(void);
+
 #endif /* MBEDTLS_SSL_TEST_IMPOSSIBLE conditions: else */
 #endif /* MBEDTLS_PROGRAMS_SSL_SSL_TEST_LIB_H */