test: fix compiler warning in NodeCryptoEnv

This fixes a warning in line 26: "warning: value computed is not used"
when calling BIO_seek().

Refs: nodejs#47160

test/cctest/test_node_crypto_env.cc

@@ -23,8 +23,9 @@ TEST_F(NodeCryptoEnv, LoadBIO) {
   Local<String> key = String::NewFromUtf8(isolate_, "abcdef").ToLocalChecked();
   node::crypto::BIOPointer bio(node::crypto::LoadBIO(*env, key));
 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
-  BIO_seek(bio.get(), 2);
-  ASSERT_EQ(BIO_tell(bio.get()), 2);
+  const int ofs = 2;
+  ASSERT_EQ(BIO_seek(bio.get(), ofs), ofs);
+  ASSERT_EQ(BIO_tell(bio.get()), ofs);
 #endif
   ASSERT_EQ(ERR_peek_error(), 0UL) << "There should not have left "
                                       "any errors on the OpenSSL error stack\n";