[Mupen64Plus] Loading ROMs Multiple Times Causes Memory Leak

Summary

During an instance of Bizhawk running, opening any ROM while using the Mupen64Plus core will cause memory to be loaded that is not cleared when either closing the ROM or using "Reboot Core". The only way to remove the memory usage is to close the istance of Bizhawk.

This appears to have been introduced in 5a8ce91d9550e82ff9e90c5569f045548041f284 , where the DLLs were recompiled for VS2022 as well as had the dependencies updated.

I tested in the latest upstream version (Mupen64Plus v2.6.0) with no issues, but as stated in their release note here the packages used were built with VS2019, so I'm unsure if it working correctly there correlates.

Repro

1. (Optional) Disable rewind if it is enabled so as not have to wait for it to fill its buffer
2. Load any ROM with the Mupen64Plus core
3. Close the ROM or select "Reboot Core"
4. Repeat steps 2-3 while taking note of Bizhawk's memory usage in Task Manager

Below are two images showcasing Ocarina of Time (USA) both on first load and after using "Reboot Core" 10 times.

Start by reviewing linked pull request #4117 and the change that recompiled the Mupen64Plus DLLs for VS2022. Reproduce the leak by repeatedly loading a ROM and closing it or selecting “Reboot Core,” while monitoring memory usage. Done means repeated cycles no longer cause unbounded memory growth.