PROGS: Fix ESTALE errors on NFS while cleaning in directories with PROGS.

PROGS: Fix ESTALE errors on NFS while cleaning in directories with PROGS.

- Only recurse on cleanobj/cleandir if there is no .OBJDIR being used.
  If we don't recurse then bsd.obj.mk will just rm -rf the OBJDIR dir.
- When recursing on cleanobj/cleandir don't remove dependfiles/dirs
  redundantly from the child and main processes.  Meaning '.depend', and
  'tags', and '.depend.*' will now only be removed from the main
  process.
- Stop recursing on 'cleandepend' since the main process can handle
  removing all files via the default glob patterns in CLEANDEPENDFILES.
- This reverts r288201, by readding recursion on 'cleanobj', due to
  r291635 changing how bsd.subdir.mk handles recursion.

This is primarily targeting ESTALE NFS errors from rm(1) during a
buildworld but is also a performance optimization as both issues fixed
were redundant anyway.

Reported by:	cperciva, scottl
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon