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 <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Don Zickus <[email protected]>
Cc: Joe Mario <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>