AsyncSSLSocketTest: Fix an LSAN error

Summary:
SSLAcceptRunnerFiberCloseSessionCb was leaking the SSL_SESSION because it set a
custom server SSL session callback handler that did not properly manage the
SSL_SESSION that it was given.

Reviewed By: modiking

Differential Revision: D33807657

fbshipit-source-id: 5eeaecfef5df1f1d281abe2918f9926a969ab84d

folly/io/async/test/AsyncSSLSocketTest.cpp

@@ -2562,7 +2562,10 @@ TEST(AsyncSSLSocketTest, SSLAcceptRunnerFiber) {
 
 static int newCloseCb(SSL* ssl, SSL_SESSION*) {
   AsyncSSLSocket::getFromSSL(ssl)->closeNow();
-  return 1;
+
+  // We do not want ownership over the supplied SSL_SESSION*, we return 0 to
+  // tell OpenSSL to free it on our behalf.
+  return 0;
 }
 
 #if FOLLY_OPENSSL_IS_110