The copy constructors are causing problems when the `fiber.stack` vector
gets reallocated when its capacity is full, since when vectors are
reallocated, the elements are moved (or copied if there's no usable move
constructor) to the reallocated memory and then the original elements
are destroyed.
This premature calling of destructors leads to double-free and
use-after-free errors.
I fixed it by deleting the copy constructors and explicitly defining
move constructors.
Not sure why, but this fixes crashes when calling variadic functions in
the Ruby API in libretro builds when Ruby is built without `-DNDEBUG`.
Maybe the previous way of calling varargs functions was undefined
behaviour somehow.
Okay, the coroutine implementation of `sandbox_malloc` is clearly
broken. It would be working if Asyncify instrumented the `memory.grow`
WebAssembly instruction, but it doesn't instrument it.
This commit reverts commit 42c4ff9497 and
also increases the default VM memory allocation from 64 MiB to 96 MiB to
account for the lack of ability to increase the memory allocation at run
time. I'll find some new way to implement increasing the memory
allocation later.
According to AddressSanitizer, when `sandbox_malloc` causes the
WebAssembly memory to grow in size, every single coroutine on the
sandbox stack gets corrupted. So if `sandbox_malloc` is going to cause
the memory to grow in size, we need to yield so that there are no
coroutines on the sandbox stack while the reallocation occurs.
