Fix unexpected lpProcessInformation output when CreateProcess failed

[RatinCN]

If CreateProcess failed, lpProcessInformation should be zeroed (Windows behavior), but the current code is returning uninitialized values (the local variable pi).

A simple way to fix this is PROCESS_INFORMATION pi = { 0 };, but this will result in an unnecessary ZeroMemory call in success path or an unnecessary CopyMemory call in fail path, so I chose another way to fix it.