perf hists: Add __hist_entry__snprintf function

perf hists: Add __hist_entry__snprintf function

Add __hist_entry__snprintf() to take a perf_hpp_list as an argument
instead of using he->hists->hpp_list.

This way we can display arbitrary list of entries regardless of the
hists setup, which will be useful in the upcoming c2c patch series.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1474558645-19956-2-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>