'make clean' used to show all the rm lines, which isn't really
informative in any way and spams the console.

Implement summary output:

  comet:~/tip/tools/perf> make clean
   CLEAN libtraceevent
   CLEAN liblk
   CLEAN config
   CLEAN core-objs
   CLEAN core-progs
   CLEAN core-gen
   CLEAN Documentation
   CLEAN python

'make clean V=1' will still show the old, detailed output.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1381312169-17354-2-git-send-email-mingo@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>