perf annotate TUI: Fix column header when toggling period/percent

We have the 't' hotkey to toggle showing either the total period or the
percentage of samples for a given line, but we forgot to toggle as well
the column header, always showing "Percent", even when showing the
period, fix it.
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1501172169-6761-1-git-send-email-treeze.taeung@gmail.com
[ Extracted from a larger patch, s/Event count/Period/g ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/annotate.c

@@ -166,7 +166,7 @@ static void annotate_browser__write(struct ui_browser *browser, void *entry, int
 		if (!show_title)
 			ui_browser__write_nstring(browser, " ", pcnt_width);
 		else
-			ui_browser__printf(browser, "%*s", 7, "Percent");
+			ui_browser__printf(browser, "%*s", 7, annotate_browser__opts.show_total_period ? "Period" : "Percent");
 	}
 	if (ab->have_cycles) {
 		if (dl->ipc)