Genie:  Omit redundant ppid arg in spawn_process()

The default is to use the parent's PID, which is invariably 1 here.
relix:  Add process::set_ppid()
Genie:  Use set_ppid() in _relix_clone()
Genie:  Remove ppid parameter from NewProcess()
Genie:  Ignore ppid in Process constructor

It's currently only set to non-zero for new threads.
Genie:  Remove ppid param from Process constructor
Merge branch 'ppid'

Call set_ppid() to handle CLONE_PARENT, and assume the parent PID is the
new process' PPID in the common path.