This hides the need to provide mutable C strings, and unifies
existing basename calls and variations in a single location.
Change-Id: Idfb449c47b1421f1a751efc3d7404f15f8b369ca
Reviewed-on: https://chromium-review.googlesource.com/725731
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
