Set up file stream for redirecting logs by adding a parameter in `set_debug`.

The stderr is used by default.

Thanks for opening this issue..I think you need to elaborate a bit more about this feature you are suggesting. In general we don't allow this kind of facilities to redirect to file stream anywhere else in the interpreter.

Thank you for the reminder.

At first, I wanted to analyze the effectiveness of GC through logs.
However, because GC through the stderr output, these logs are mixed in with other output(such as warnings). This make it difficult to handle them automaticaly.

So, i added an `TestIOWrapper` parameter(Not just file streams, but also other io, sockets, buffer and so on) to `set_debug` function in gcmodule.c, to redirect GC logs.

I think this will help developers monitor the GC more easily, for example when they deal with a memory leak.

Of course, the default will remain the same as the previous behavior , log via stderr :)

Sorry, parameter type is `TextIOWrapper`, not `TestIOWrapper`

There are several problems with this change:

1) The lifetime of the file descriptor. The file descriptor is borrowed, which normally will lead to not being properly cleaned upon failure or interpreter deallocation.

2) The statistics you are trying to fetch via parsing the file are actually available through better APIS:

https://docs.python.org/3/library/gc.html#gc.callbacks
and
https://docs.python.org/3/library/gc.html#gc.get_stats

3) The stderr output is not stable or considered to be stable between releases. The main purpose is to serve as a quick way to debug or check for statistics without using proper callbacks, but enything more involved needs to use the callbacks.

Based on these, I am afraid I don't feel comfortable supporting this patch :(

There is another problem: PySys_WriteStderr is faster than your gc_log, which can potentially slow down heavy GC-based programs, even if the file descriptor is not used.