Wasmer can't run non-wasi files (master)

[syrusakbary]

Describe the bug

I think due to latest changes in WASI. detection wasmer is no longer able to run simple files:

➜ ./target/release/wasmer tests/examples/fac.wat
error: failed to run `tests/examples/fac.wat`
│   1: WASI execution failed
╰─> 2: The WASI version could not be determined

[MarkMcCaskey]

Good catch, we should definitely have an integration test for this (since we clearly don't right now)

[MarkMcCaskey]

Oh! This edge case is far more subtle, the bug is specifically WASI ABIs that don't have any WASI imports, we fail to detect anything so say that it "isn't WASI", I suppose we should default to the latest ABI in that case

Type: wat
Size: 523 B
Imports:
  Functions:
  Memories:
  Tables:
  Globals:
Exports:
  Functions:
    "_start": [] -> [I32]
  Memories:
  Tables:
  Globals:

This is the heuristic of exported functions specifying which ABI breaking down. I'm rather surprised that this worked with the old logic to be honest!