build.rs: remove coreutils stuff

[cakebaker]

This PR removes some coreutils stuff from build.rs that's not needed in util-linux.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (c1bf33d) to head (07d7534).
Report is 3 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff     @@
##   main   #265   +/-   ##
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