perf hists: Resort after filtering hierarchy

In hierarchy mode, a filter can affect periods of entries in upper
hierarchy.  So it needs to resort the hists after filter.

For example, let's look at following example:

 Overhead      Command / Shared Object / Symbol
 ------------  --------------------------------
 30.00%        perf
    20.00%        perf
       10.00%        main
        5.00%        pr_debug
        5.00%        memcpy
    10.00%        [kernel.vmlinux]
        8.00%        memset
        2.00%        cpu_idle

If we apply simbol filter for 'mem' it should look like this

 13.00%        perf
     8.00%        [kernel.vmlinux]
        8.00%        memset
     5.00%        perf
        5.00%        memcpy

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1456326830-30456-8-git-send-email-namhyung@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>