Building multiple ort-sys with download-binaries may fail

[qryxip]

When you use ort with download-binaries both in dependencies and in build-dependencies, in the following code, in-progress lib_dir may be used.

ort/ort-sys/build.rs

Lines 462 to 467 in 548bfed

	let lib_dir = cache_dir.join(ORT_EXTRACT_DIR);
	if !lib_dir.exists() {
	let downloaded_file = fetch_file(prebuilt_url);
	assert!(verify_file(&downloaded_file, prebuilt_hash), "hash of downloaded ONNX Runtime binary does not match!");
	extract_tgz(&downloaded_file, &cache_dir);
	}

Perhaps fetch-models has the same problem.

Solutions I come up with

1. Lock lib_dir with fs4 or something

   FYI, Cargo calls flock(2) and FileLockExt directly.

2. Extract the TGZ in a temporary directory and move it to lib_dir

3. Detect if lib_dir is in-progress and just panic with a human readable message

Reproduction

Not yet, but I feel it happens for EPs.

[decahedron1]

Should be fixed by eb51646 (& effd7a7)