x/tools/internal/robustio: TestFileInfo missing feature guards for symlinks and hard-links

[bcmills]

Go version

N/A

What operating system and processor architecture are you using (go env)?

N/A

What did you do?

Check x/tools build status on https://ci.chromium.org/p/golang/g/x-tools-gotip/console.

What did you expect to see?

All tests passing.

What did you see instead?

https://ci.chromium.org/ui/p/golang/builders/ci/x_tools-gotip-wasip1-wasm_wasmtime/b8761809133576738257/test-results:

=== RUN   TestFileInfo
    robustio_test.go:57: can't create symbolic link: symlink /tmp/TestFileInfo2274051770/002/real /tmp/TestFileInfo2274051770/004/symlink: Operation not permitted
--- FAIL: TestFileInfo (2.00s)

In general calls to os.Symlink and os.Link can fail on certain configurations of Windows, Android, and wasip1. See testenv.HasSymlink and testenv.HasLink in the main repo.

(attn @findleyr @adonovan)

[gopherbot]

Change https://go.dev/cl/549555 mentions this issue: cmd/guru,internal/robustio: make tests robust to os.Symlink errors