I ran into a need for this when running stress-ng against the system.
This change implements the full functionality of scandir, where it
accepts a selection callback, as well as a comparison callback.
These can be used to trim and sort the entries from the directory
that we are being asked to enumerate. A test was also included to
validate the new functionality.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
