perf intel-pt: Fix endless record after being terminated

In __cmd_record(), when receiving SIGINT(ctrl + c), a 'done' flag will
be set and the event list will be disabled by evlist__disable() once.

While in auxtrace_record.read_finish(), the related events will be
enabled again, if they are continuous, the recording seems to be endless.

If the intel_pt event is disabled, we don't enable it again here.

Before the patch:

  huawei@huawei-2288H-V5:~/linux-5.5-rc4/tools/perf$ ./perf record -e \
  intel_pt//u -p 46803
  ^C^C^C^C^C^C

After the patch:

  huawei@huawei-2288H-V5:~/linux-5.5-rc4/tools/perf$ ./perf record -e \
  intel_pt//u -p 48591
  ^C[ perf record: Woken up 0 times to write data ]
  Warning:
  AUX data lost 504 times out of 4816!

  [ perf record: Captured and wrote 2024.405 MB perf.data ]
Signed-off-by: Wei Li <liwei391@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Tan Xiaojun <tanxiaojun@huawei.com>
Cc: stable@vger.kernel.org # 5.4+
Link: http://lore.kernel.org/lkml/20200214132654.20395-2-adrian.hunter@intel.com
[ ahunter: removed redundant 'else' after 'return' ]
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/x86/util/intel-pt.c

@@ -1173,9 +1173,12 @@ static int intel_pt_read_finish(struct auxtrace_record *itr, int idx)
 	struct evsel *evsel;
 
 	evlist__for_each_entry(ptr->evlist, evsel) {
-		if (evsel->core.attr.type == ptr->intel_pt_pmu->type)
+		if (evsel->core.attr.type == ptr->intel_pt_pmu->type) {
+			if (evsel->disabled)
+				return 0;
 			return perf_evlist__enable_event_idx(ptr->evlist, evsel,
 							     idx);
+		}
 	}
 	return -EINVAL;
 }