perf hists browser: Fix off-by-two bug on the first column

The commit 5395a048 ("perf hists: Separate overhead and baseline
columns") makes the "Overhead" column no more the first one.  So it
resulted in the mis-aligned column in the normal (non-diff) output.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/None


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