Crash when closing the main window while debugging with Visual Studio

[Wade7wastaken]

Steps:

1. Start debugging mupen with Visual Studio. Other debuggers might work for this but I don't know.
2. Open settings (Options -> Settings). This is the only way I've found to make this crash reliable.
3. Close the main window with either the x button or alt+f4
4. Observe crash in Visual Studio

I know this is a crash in an nvidia dll, and it might not be able to be reproduced by everyone, but it's annoying enough to me to open an issue about it. This issue is very low priority because it really only affects debugging.

There are also a few other crashes I've encountered while closing mupen. I can't find any consistent way to reproduce these, but they were both from closing mupen right after loading a rom.

[Aurumaker72]

A similar but not identical crash happens inside GetMessage, withSTATUS_FATAL_USER_CALLBACK_EXCEPTION

[Aurumaker72]

This is caused by lack of synchronization when pushing VI and frame times to the circular buffers (circular_push)

[Aurumaker72]

Can't repro any crashes related to this after 87313382a1cbf76967db551bde843c9769027313

[Aurumaker72]

Now it's crashing in nvidia usermode driver

[Aurumaker72]

Problem comes at least partially from emu thread not being closed before exiting.

The emu thread keeps barreling along while main thread is calling C++ destructors, and it rips various resources from right under its feet

[Aurumaker72]

This issue comes from Direct64, not sure how much can be done here.