Implementation bug of boost::process::limit_handles on Windows

From "boost/process/detail/windows/handles.hpp", there are these codes.

```
template
void on_setup(Executor & exec) const
{
auto all_handles = get_handles();
foreach_used_handle(exec,
[&](::boost::winapi::HANDLE_ handle)
{
auto itr = std::find(all_handles.begin(), all_handles .end(), handle);
::boost::winapi::DWORD_ flags = 0u;
if (itr != all_handles.end())
*itr = ::boost::winapi::INVALID_HANDLE_VALUE_;
else if ((::boost::winapi::GetHandleInformation(*itr, &flags) != 0)
&&((flags & ::boost::winapi::HANDLE_FLAG_INHERIT_) == 0)) //it is NOT inherited anyhow, so ignore too
*itr = ::boost::winapi::INVALID_HANDLE_VALUE_;
});

auto part_itr = std::partition(all_handles.begin(), all_handles.end(),
[](::boost::winapi::HANDLE_ handle) {return handle != ::boost::winapi::INVALID_HANDLE_VALUE_;});

all_handles.erase(part_itr, all_handles.end()); //remove invalid handles
handles_with_inherit_flag = std::move(all_handles);

for (auto handle : handles_with_inherit_flag)
::boost::winapi::SetHandleInformation(handle, ::boost::winapi::HANDLE_FLAG_INHERIT_, 0);
}
```

See: 'if (itr != all_handles.end()) ... else do with *itr', the else condition.
The 'itr' is 'end()' now, so we can't handle on the reference of it.

I think they should be:

```
foreach_used_handle(exec,
[&](::boost::winapi::HANDLE_ handle)
{
auto itr = std::find(all_handles.begin(), all_handles .end(), handle);
DWORD flags = 0u;
if (itr != all_handles.end())
*itr = ::boost::winapi::INVALID_HANDLE_VALUE_;
});
for (auto& h : all_handles) {
DWORD flags = 0u;
if ((h != ::boost::winapi::INVALID_HANDLE_VALUE_)
&& (::boost::winapi::GetHandleInformation(h, &flags) != 0)
&& ((flags & ::boost::winapi::HANDLE_FLAG_INHERIT_) == 0)) //it is NOT inherited anyhow, so ignore too
h = ::boost::winapi::INVALID_HANDLE_VALUE_;
}

```