Correctly resolve temp files on macOS
Correctly resolve temp files on macOS

On macOS, the `$TMPDIR` is in `/var`. However, `/var -> /private/var`.
This means that fully resolved temp filenames weren't always getting
checked against the proper prefix.

This was affecting some of the Haskell plugins, though I'm sure it could
have affected any program that resolved past the generated `$TMPDIR/foo`
and wound up at a different filename.

esran/ale,neersighted/ale,hernot/ale,IngoHeimbach/ale,hernot/ale,hernot/ale,IngoHeimbach/ale,w0rp/ale,w0rp/ale,IngoHeimbach/ale,w0rp/ale,adriaanzon/ale,doits/ale,neersighted/ale,neersighted/ale