Add MBEDTLS_ALLOW_PRIVATE_ACCESS to test programs

Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index afe0118..91c231f 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -23,6 +23,8 @@
  * example of good general usage.
  */
 
+#define MBEDTLS_ALLOW_PRIVATE_ACCESS
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else