Pull in <linux/capsicum.h> rather than local copy of capability constants.
Pull in <linux/procdesc.h> rather than use local copy of PD_DAEMON
Cope with ENOMEM from mlockall(2)
Add test that process descriptor fails appropriately on normal read/write.

Also commonize termination of child process in PipePdfork tests.
Add tests of rights checking for process descriptor syscalls
Add initial pdwait4() test, and clarify different behaviors on wait