Merge development commit 8e76332 into development-psa

Additional changes to temporarily enable running tests:
ssl_srv.c and test_suite_ecdh use mbedtls_ecp_group_load instead of
mbedtls_ecdh_setup
test_suite_ctr_drbg uses mbedtls_ctr_drbg_update instead of 
mbedtls_ctr_drbg_update_ret
diff --git a/include/mbedtls/xtea.h b/include/mbedtls/xtea.h
index 6430c13..b47f553 100644
--- a/include/mbedtls/xtea.h
+++ b/include/mbedtls/xtea.h
@@ -121,6 +121,8 @@
                     unsigned char *output);
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
 
+#if defined(MBEDTLS_SELF_TEST)
+
 /**
  * \brief          Checkup routine
  *
@@ -128,6 +130,8 @@
  */
 int mbedtls_xtea_self_test( int verbose );
 
+#endif /* MBEDTLS_SELF_TEST */
+
 #ifdef __cplusplus
 }
 #endif