perf hists: Add line argument into perf_hpp_fmt's header callback

perf hists: Add line argument into perf_hpp_fmt's header callback

Adding line argument into perf_hpp_fmt's header callback to be able to
request specific header line.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1470583710-1649-3-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>