perf hists: Reimplement hists__has_callchains()

There are places where we have only access to struct hists and need to
know if any of its hist_entries has callchains, like when drawing
headers for the various output modes (stdio, TUI, etc), so, when adding
a new hist_entry, check if it has callchains, storing this info for
later use by hists__has_callchains().

This reimplementation is necessary because not always a 'struct hists'
is allocated together with a 'struct perf evsel', so we can't go from
'hists' to 'perf_event_attr.sample_type & PERF_SAMPLE_CALLCHAIN'.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jin Yao <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: https://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/hist.c

···
 		.raw_data = sample->raw_data,
 		.raw_size = sample->raw_size,
 		.ops = ops,
-	};
+	}, *he = hists__findnew_entry(hists, &entry, al, sample_self);
 
-	return hists__findnew_entry(hists, &entry, al, sample_self);
+	if (!hists->has_callchains && he && he->callchain_size != 0)
+		hists->has_callchains = true;
+	return he;
 }
 
 struct hist_entry *hists__add_entry(struct hists *hists,

tools/perf/util/hist.h

···
 	struct events_stats	stats;
 	u64			event_stream;
 	u16			col_len[HISTC_NR_COLS];
+	bool			has_callchains;
 	int			socket_filter;
 	struct perf_hpp_list	*hpp_list;
 	struct list_head	hpp_formats;
···
 
 static __pure inline bool hists__has_callchains(struct hists *hists)
 {
-	const struct perf_evsel *evsel = hists_to_evsel(hists);
-	return evsel__has_callchain(evsel);
+	return hists->has_callchains;
 }
 
 int hists__init(void);