Fix stalled pipe on Windows when using target quality

[woot000]

This is my first time making changes to Rust code, so let me know if the styling is wrong or if I made a glaring mistake with this change. It works perfectly on my machine

[redzic]

The cause of this problem appears to be related to rust-lang/rust#45572, where the pipe buffer becomes full, blocking further output. The only problem I have with this approach is that we lose the error reporting from the stderr of the child processes, so debugging any issues with target quality crashes would become a big pain without any error messages to go off of.

Perhaps we could look into some other solution for handling this? I would ideally want something that fixes this while keeping the error reporting that we currently have.

[woot000]

I suppose stderr could be redirected to a file, though that would necessitate a lot of changes to the vmaf_probe function, which is out of the scope of my abilities for Rust coding

I think for the time being, this is okay as a temporary fix

[redzic]

Sorry for the extremely slow response, I'll merge this as a temporary fix while I look for a solution that has proper error handling/reporting.