The pull request macOS lane runs the darwin suite: the differential corpus
plus every file whose assertions take darwin-specific branches. The library
suites (library-multi, library-callbacks, library-dispatch) take the Mach-O
localization and link arms on darwin, and the runtime string oracle checks
the arm64 parseInt answers, but none of them were in the list, so changes
that broke them on macOS reached main before a macOS run saw them. Add the
four files to darwinFiles.