perf stat: Do not allow --for-each-cgroup without cpu

The cgroup mode should work with cpu events.  Warn if --for-each-cgroup
option is used with a task target like existing -G option.

  # perf stat --for-each-cgroup . sleep 1
  both cgroup and no-aggregation modes only available in system-wide mode

   Usage: perf stat [<options>] [<command>]

      -G, --cgroup <name>   monitor event in cgroup name only
      -A, --no-aggr         disable CPU count aggregation
      -a, --all-cpus        system-wide collection from all CPUs
          --for-each-cgroup <name>
                            expand events for each cgroup
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210830170200.55652-1-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-stat.c

@@ -2386,7 +2386,8 @@ int cmd_stat(int argc, const char **argv)
 	 * --per-thread is aggregated per thread, we dont mix it with cpu mode
 	 */
 	if (((stat_config.aggr_mode != AGGR_GLOBAL &&
-	      stat_config.aggr_mode != AGGR_THREAD) || nr_cgroups) &&
+	      stat_config.aggr_mode != AGGR_THREAD) ||
+	     (nr_cgroups || stat_config.cgroup_list)) &&
 	    !target__has_cpu(&target)) {
 		fprintf(stderr, "both cgroup and no-aggregation "
 			"modes only available in system-wide mode\n");
@@ -2394,6 +2395,7 @@ int cmd_stat(int argc, const char **argv)
 		parse_options_usage(stat_usage, stat_options, "G", 1);
 		parse_options_usage(NULL, stat_options, "A", 1);
 		parse_options_usage(NULL, stat_options, "a", 1);
+		parse_options_usage(NULL, stat_options, "for-each-cgroup", 0);
 		goto out;
 	}