CA-38105: Fix segfault in fork-and-exec-daemon.
CA-38105: Fix segfault in fork-and-exec-daemon.

The segfault would have happened when a message was receieved on this socket without an associated fd being sent. This is bad behaviour on the part of the client, but shouldn't cause a segfault. This patch fixes the segfault, but we'll need to fix the client too!

Signed-off-by: Jon Ludlam <Jonathan.Ludlam@eu.citrix.com

johnelse/forkexecd,xapi-project/message-switch,djs55/forkexecd,xapi-project/message-switch,xapi-project/message-switch