Remove fts sorting.  It was originally put there to copy files
before directories since files (usually) are in the same cylinder
group and subdirectories aren't.  However, this mostly changed with
the new ffs dirpref algorithm in 2001.

No sorting has two effects:
1) copy appears to be somewhat faster (e.g. on my laptop cp'ing build
  objdir to tmpfs is 7% faster after the change)
2) source file parameters no longer get randomly shuffled due to
  fts doing an unstable sort of them.  this means that
  "cp 1 2 3 4 dest/" will copy the files in that order instead
  of e.g. 3 4 1 2.

(pooka)