Support recent wasmtime scheme

[Gabor Greif]

Recent changes to wasmtime include the invocation of _start.
The (start $<entry>) directive in the .wasm file is only invoked once, to run the constructors (for initialising the heap and vars).

So when there is a _start I'd suggest that run gets following meaning:

• invoke (start $<entry>), if not done yet, remember it
• invoke _start.

[Gabor Greif]

Currently I have the choice:

• run -> only runs (start $<entry>)
• run _start -> won't run (start $<entry>), but _start and the necessary globals are not set up.

[Yuta Saito]

Sorry for my late response. I applied this startup scheme. Please check it in master branch 🙏

[Gabor Greif]

Yes, this works now. Thanks for the fix!