Treat exit code 128 (ERROR_WAIT_NO_CHILDREN) as non-fatal on Win32,

Treat exit code 128 (ERROR_WAIT_NO_CHILDREN) as non-fatal on Win32,
since it can happen when a process fails to start when the system
is under high load.

Per several bug reports and many peoples investigation.

Back-patch to 8.4, which is as far back as the "deadman-switch"
for shared memory access exists.