GPDB uses libcurl-gnutls.so.4 as default libcurl on ubuntu. gpfdist SSL
connection reports error (56 - Failure when receiving data from the peer)
on handling POST message. We find it shutdown socket directly without sending
close_notify to client. So we call SSL_shutdown() before socket shutdown.

But SSL_accept() will return error with above patch on Centos, because
GPDB curl reuses SSL session ID in the second client hello, but server considers
that session is shutdown, so it won't accept that session ID.
The solution is disabling SSL session ID cache by setting curl option.
Then both Centos and ubuntu work well.

Enable gpfdist SSL test case.