test: ensure X509 has no dependency on BIGNUM when built without MBEDTLS_DEPRECATED_REMOVED

Signed-off-by: Valerio Setti <vsetti@baylibre.com>

tests/scripts/all.sh

@@ -1767,6 +1767,9 @@ component_test_full_no_deprecated () {
 
     msg "test: make, full_no_deprecated config" # ~ 5s
     make test
+
+    msg "test: ensure that X509 has no direct dependency on BIGNUM_C"
+    not grep mbedtls_mpi library/libmbedx509.a
 }
 
 component_test_full_no_deprecated_deprecated_warning () {