When a command-line filter is applied in hierarchy mode, output is
broken especially when filtering on lower level.  The higher level
entries doesn't show up so it's hard to see the results.

Also it needs to handle multi sort keys in a single hierarchy level.

Before:

  $ perf report --hierarchy -s 'cpu,{dso,comm}' --comms swapper --stdio
  ...
  #    Overhead  CPU / Shared Object+Command
  # ...........  ...........................
  #
         13.79%     [kernel.vmlinux]  swapper
      31.71%     000
         13.80%     [kernel.vmlinux]  swapper
          0.43%     [e1000e]          swapper
         11.89%     [kernel.vmlinux]  swapper
          9.18%     [kernel.vmlinux]  swapper

After:

  #    Overhead  CPU / Shared Object+Command
  # ...........  ...............................
  #
      33.09%     003
         13.79%     [kernel.vmlinux]  swapper
      31.71%     000
         13.80%     [kernel.vmlinux]  swapper
          0.43%     [e1000e]          swapper
      21.90%     002
         11.89%     [kernel.vmlinux]  swapper
      13.30%     001
          9.18%     [kernel.vmlinux]  swapper
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1457531222-18130-4-git-send-email-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>