Fix tests to work in Mbed OS test environment
Update x509parse and x509write test suites to include "x509.c" from
correct location.
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index b0e0969..bd1ddbf 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -9,7 +9,11 @@
/* We need to include x509.c because we are testing x509 internal
* functions from x509_internal.h which are static. With this include
* we get the tested functions defined. */
+#if defined(TEST_ENV_MBED_OS)
+#include "../src/x509.c"
+#else
#include "../library/x509.c"
+#endif
#if defined(MBEDTLS_RSA_C)
int mbedtls_rsa_decrypt_func( void *ctx, int mode, size_t *olen,