Add ifdef for selftest in header file
See https://github.com/ARMmbed/mbedtls/pull/975
diff --git a/include/mbedtls/poly1305.h b/include/mbedtls/poly1305.h
index babbc15..abe3690 100644
--- a/include/mbedtls/poly1305.h
+++ b/include/mbedtls/poly1305.h
@@ -164,6 +164,7 @@
size_t ilen,
unsigned char mac[16] );
+#if defined(MBEDTLS_SELF_TEST)
/**
* \brief The Poly1305 checkup routine.
*
@@ -171,6 +172,7 @@
* \return \c 1 on failure.
*/
int mbedtls_poly1305_self_test( int verbose );
+#endif /* MBEDTLS_SELF_TEST */
#ifdef __cplusplus
}