perf hists: Fix formatting of long symbol names

perf hists: Fix formatting of long symbol names

We had a hardcoded buffer for formatting histogram entries, truncating
long symbol names (C++ anyone?).

Fix it by using hists__sort_list_width() before formatting the first
histogram entry to calculate the max lenght needed by traversing the
overheads and columns lists (sort order).

Reported-by: Stephane Eranian <eranian@google.com>
Tested-by: Stephane Eranian <eranian@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-vdfkkyfdp8rboh7j9344o3ss@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>