PR #585 moved the execution of a `_start` function to the CLI rather than have it automatically invoked by module instantiation. Unfortunately, this broke the WASI test programs that were relying on this behavior from instantiation. This fixes it by adding an invocation of the `_start` function in the test runner. Fixes #698.
This is the test-programs crate, which builds and runs whole programs
compiled to wasm32-wasi.