std.Io.Threaded: move the NtDelayExecution later in batchWait

also guard against receiving SUCCESS with 0 byte read

ms docs say that pipes can do this if there is a 0 byte write
fdf1ee973eAndrew Kelley committed on 1/31/2026, 6:03:14 AMparent2fb224c
2 files changedLine totals unavailable