perf stat: Fix out of bounds array access in the print_counters() evlist method

Fix a compile error on F32 and gcc version 10.1 on s390 in file
utils/stat-display.c.  The error does not show up with make DEBUG=y.  In
fact the issue shows up when using both compiler options -O6 and
-D_FORTIFY_SOURCE=2 (which are omitted with DEBUG=Y).

This is the offending call chain:

print_counter_aggr()
  printout(config, -1, 0, ...)  with 2nd parm id set to -1
    aggr_printout(config, x, id --> -1, ...) which leads to this code:
		case AGGR_NONE:
                if (evsel->percore && !config->percore_show_thread) {
                        ....
                } else {
                        fprintf(config->output, "CPU%*d%s",
                                config->csv_output ? 0 : -7,
                                evsel__cpus(evsel)->map[id],
				                        ^^ id is -1 !!!!
                                config->csv_sep);
                }

This is a compiler inlining issue which is detected on s390 but not on
other plattforms.

Output before:

 # make util/stat-display.o
    .....

  util/stat-display.c: In function ‘perf_evlist__print_counters’:
  util/stat-display.c:121:4: error: array subscript -1 is below array
      bounds of ‘int[]’ [-Werror=array-bounds]
  121 |    fprintf(config->output, "CPU%*d%s",
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  122 |     config->csv_output ? 0 : -7,
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  123 |     evsel__cpus(evsel)->map[id],
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  124 |     config->csv_sep);
      |     ~~~~~~~~~~~~~~~~
  In file included from util/evsel.h:13,
                 from util/evlist.h:13,
                 from util/stat-display.c:9:
  /root/linux/tools/lib/perf/include/internal/cpumap.h:10:7:
  note: while referencing ‘map’
   10 |  int  map[];
      |       ^~~
  cc1: all warnings being treated as errors
  mv: cannot stat 'util/.stat-display.o.tmp': No such file or directory
  make[3]: *** [/root/linux/tools/build/Makefile.build:97: util/stat-display.o]
  Error 1
  make[2]: *** [Makefile.perf:716: util/stat-display.o] Error 2
  make[1]: *** [Makefile.perf:231: sub-make] Error 2
  make: *** [Makefile:110: util/stat-display.o] Error 2
  [root@t35lp46 perf]#

Output after:

  # make util/stat-display.o
    .....
  CC       util/stat-display.o
  [root@t35lp46 perf]#

Committer notes:

Removed the removal of {} enclosing the multiline else block, as pointed
out by Jiri Olsa.
Suggested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20200825063304.77733-1-tmricht@linux.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/stat-display.c

@@ -117,7 +117,7 @@ static void aggr_printout(struct perf_stat_config *config,
 				cpu_map__id_to_die(id),
 				config->csv_output ? 0 : -3,
 				cpu_map__id_to_cpu(id), config->csv_sep);
-		} else {
+		} else if (id > -1) {
 			fprintf(config->output, "CPU%*d%s",
 				config->csv_output ? 0 : -7,
 				evsel__cpus(evsel)->map[id],