perf tools: Fix column width setting on 'trace' sort key

It missed to update column length of the 'trace' sort key in the
hists__calc_col_len() so it might truncate the output.  It calculated
the column length in the ->cmp() callback originally but it doesn't
guarantee it's called always.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1456064558-13086-5-git-send-email-namhyung@kernel.org


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