sockfilt.c: fixed and simplified Windows select function

Since the previous complex select function with initial support for
non-socket file descriptors, did not actually work correctly for
Console handles, this change simplifies the whole procedure by using
an internal waiting thread for the stdin console handle.

The previous implementation made it continuously trigger for the stdin
handle if it was being redirected to a parent process instead of
an actual Console input window.

This approach supports actual Console input handles as well as
anonymous Pipe handles which are used during input redirection.

It depends on the fact that ReadFile supports trying to read zero bytes
which makes it wait for the handle to become ready for reading.