Fix TSModule tracking.

[maleadt]

This should be NFC, but lets see if CI still fails.

[maleadt]

If this doesn't help, we may have to change how we handle contexts / thread-safe contexts. It's currently possibly to have a context() not matching the ts_context(), which seems like it could result in nasty errors. I wonder if we should simply make it so that ts_context() always returns a (uniqued) thread-safe version of the current context.

[maleadt]

I wonder if we should simply make it so that ts_context() always returns a (uniqued) thread-safe version of the current context.

That doesn't work, the ThreadSafeContext ctor taking a Context transfers ownership...

Switching everything around and only using ThreadSafeContexts in LLVM.jl would be possible, but that's a pretty invasive change. It would also make it impossible to take a foreign context and work with that, because once again we can't create a TSCtx wrapping it.