While they usually are not included in a normal strongSwan build, the XPC
header indirectly defines these Mach types. To build charon-xpc, which uses
both XPC and strongSwan includes, we have to redefine these types.
To make accept/recvmsg cancelable, we wrap them with poll. As poll itself
does not honor pending cancellations when entering the function, we use our
variant that checks for pending cancellation requests before entering poll().
Martin Willi