We lost that when we move it outside hist_entry__snprintf, but better
leave it untangled of 'perf diff' stuff (pair_hist, etc).

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.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-qlhb6ictf5twykog6x344s0b@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>