Make cl-fad do the right thing if TMPDIR changes between build time and run time
Make cl-fad do the right thing if TMPDIR changes between build time and run time

For example, if built in nix TMPDIR is set to a directory within the
build dir.  We don't want to preserve that at runtime!

bradleyjensen/shcl,bradleyjensen/shcl,bradleyjensen/shcl