Merge pull request #2511 from tmael/BN_bn2hex

Fix for hex digits with fastmath and normal integer

tests/api.c

@@ -24123,7 +24123,11 @@ static void test_wolfSSL_X509_get_serialNumber(void)
     X509_free(x509); /* free's a */
 
     AssertNotNull(serialHex = BN_bn2hex(bn));
+#ifndef WC_DISABLE_RADIX_ZERO_PAD
+    AssertStrEQ(serialHex, "01");
+#else
     AssertStrEQ(serialHex, "1");
+#endif
     OPENSSL_free(serialHex);
 
     AssertIntEQ(BN_get_word(bn), 1);