perf script: Add --show-cgroup-events option

The --show-cgroup-events option is to print CGROUP events in the
output like others.

Committer testing:

  [root@seventh ~]# perf record --all-cgroups --namespaces /wb/cgtest
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.039 MB perf.data (487 samples) ]
  [root@seventh ~]# perf script --show-cgroup-events | grep PERF_RECORD_CGROUP -B2 -A2
           swapper     0     0.000000: PERF_RECORD_CGROUP cgroup: 1 /
              perf 12145 11200.440730:          1 cycles:  ffffffffb900d58b __intel_pmu_enable_all.constprop.0+0x3b (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
              perf 12145 11200.440733:          1 cycles:  ffffffffb900d58b __intel_pmu_enable_all.constprop.0+0x3b (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
  --
            cgtest 12145 11200.440739:     193472 cycles:  ffffffffb90f6fbc commit_creds+0x1fc (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
            cgtest 12145 11200.440790:    2691608 cycles:      7fa2cb43019b _dl_sysdep_start+0x7cb (/usr/lib64/ld-2.29.so)
            cgtest 12145 11200.440962: PERF_RECORD_CGROUP cgroup: 83 /sub
            cgtest 12147 11200.441054:          1 cycles:  ffffffffb900d58b __intel_pmu_enable_all.constprop.0+0x3b (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
            cgtest 12147 11200.441057:          1 cycles:  ffffffffb900d58b __intel_pmu_enable_all.constprop.0+0x3b (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
  --
            cgtest 12148 11200.441103:      10227 cycles:  ffffffffb9a0153d end_repeat_nmi+0x48 (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
            cgtest 12148 11200.441106:     273295 cycles:  ffffffffb99ecbc7 copy_page+0x7 (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
            cgtest 12147 11200.441133: PERF_RECORD_CGROUP cgroup: 88 /sub/cgrp1
            cgtest 12147 11200.441143:    2788845 cycles:  ffffffffb94676c2 security_genfs_sid+0x102 (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
            cgtest 12148 11200.441162: PERF_RECORD_CGROUP cgroup: 93 /sub/cgrp2
            cgtest 12148 11200.441182:    2669546 cycles:            401020 _init+0x20 (/wb/cgtest)
            cgtest 12149 11200.441247:          1 cycles:  ffffffffb900d58b __intel_pmu_enable_all.constprop.0+0x3b (/lib/modules/5.6.0-rc6-00008-gfe2413eefd7f/build/vmlinux)
  [root@seventh ~]#

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200325124536.2800725-10-namhyung@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>