perf map: Introduce map__has_symbols()

To further simplify checking if symbols are available for a given map
and to reduce the number of users of MAP__{FUNCTION,VARIABLE}.

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: https://lkml.kernel.org/n/tip-iyfoyvbfdti5uehgpjum3qrq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/map.c

@@ -259,6 +259,11 @@ bool __map__is_kernel(const struct map *map)
 	return __machine__kernel_map(map->groups->machine, map->type) == map;
 }
 
+bool map__has_symbols(const struct map *map)
+{
+	return dso__has_symbols(map->dso, map->type);
+}
+
 static void map__exit(struct map *map)
 {
 	BUG_ON(!RB_EMPTY_NODE(&map->rb_node));