Fix assertion failure for SSL connections.

Commit cfdf4dc added an assertion that every WaitLatch() or similar
handles postmaster death.  One place did not, but was missed in
review and testing due to the need for an SSL connection.  Fix, by
asking for WL_EXIT_ON_PM_DEATH.

Reported-by: Christoph Berg
Discussion: https://postgr.es/m/20181124143845.GA15039%40msg.df7cb.de

Author: macdice

src/backend/libpq/be-secure-openssl.c

@@ -406,9 +406,9 @@ be_tls_open_server(Port *port)
 				 * StartupPacketTimeoutHandler() which directly exits.
 				 */
 				if (err == SSL_ERROR_WANT_READ)
-					waitfor = WL_SOCKET_READABLE;
+					waitfor = WL_SOCKET_READABLE | WL_EXIT_ON_PM_DEATH;
 				else
-					waitfor = WL_SOCKET_WRITEABLE;
+					waitfor = WL_SOCKET_WRITEABLE | WL_EXIT_ON_PM_DEATH;
 
 				(void) WaitLatchOrSocket(MyLatch, waitfor, port->sock, 0,
 										 WAIT_EVENT_SSL_OPEN_SERVER);