Fix calling pathBasename twice during loadOrderSort

[zodern]

For a medium sized app on Windows, these are some times from sorting files in 3 architectures during full rebuilds:
Before: 153ms, 140, 358, 391, 219, 177

After removing duplicate files.pathBasename: 84ms, 58, 73, 49, 114, 88

In the future, an additional optimization we could consider is using path.posix.basename instead of files.pathBasename. files.pathBasename converts paths to the os style path, then uses the basename function for the os. This conversion is probably unnecessary since all paths should be in posix format and are relative.

With posix basename: 57ms, 38, 25, 30, 40, 70, 43