[dash] Run builtin ls, cp, mv, etc last

This change lets clients replace the built-in versions of ls and the other core
utils with more complete versions.

Change-Id: I6d7b0c1bdd1d3f56199034c15c60cb983cb2b006

[dash] Import dash 0.5.9.1

This is dash at revision afe0e0152e4dc12d84be3c02d6d62b0456d68580 from
http://git.kernel.org/cgit/utils/dash/dash.git/

Change-Id: I640f85e59520531ad7c65b7b35f00651e5cbc5d9