Free Windows library handles when we free_all in a module

Tor frees most resources on shutdown, using module *_free_all functions.

But we don't free Windows library handles.

Here's what we'd need to do:

• write a generic function for freeing Windows library handles in winlib.c
• call that function to free all the library handles, after we've finished using functions from those libraries

This change would only affect compat_time.c and ntmain.c. They don't currenly have *_free_all functions.

This is low-priority, because Windows libraries are reference-counted. And the two libraries that tor uses are needed for the life of the process.

For details, see https://docs.microsoft.com/en-us/windows/desktop/api/libloaderapi/nf-libloaderapi-freelibrary