It will help for us to rename earlier vs later, and syscallfs will be
laborious, especially after we introduce an FSConfig type and need to
declare a method name that differentiates from normal fs.FS. e.g. WithFS
vs WithSysFS reads nicer than WithSyscallFS, and meanwhile sys is
already a public package.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
