perf db-export: No need to have ->thread twice in struct export_sample

As it comes from address_location->thread, that is already stored as
export_sample->al, where the thread can be obtained.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20150402141542.GA9630@kernel.org
Link: http://lkml.kernel.org/n/tip-bzotbl4epoztw0jd6sm2stpf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/db-export.c

@@ -289,7 +289,6 @@ int db_export__sample(struct db_export *dbe, union perf_event *event,
 		.event = event,
 		.sample = sample,
 		.evsel = evsel,
-		.thread = thread,
 		.al = al,
 	};
 	struct thread *main_thread;

tools/perf/util/db-export.h

@@ -34,7 +34,6 @@ struct export_sample {
 	union perf_event	*event;
 	struct perf_sample	*sample;
 	struct perf_evsel	*evsel;
-	struct thread		*thread;
 	struct addr_location	*al;
 	u64			db_id;
 	u64			comm_db_id;

tools/perf/util/scripting-engines/trace-event-python.c

@@ -679,7 +679,7 @@ static int python_export_sample(struct db_export *dbe,
 	tuple_set_u64(t, 0, es->db_id);
 	tuple_set_u64(t, 1, es->evsel->db_id);
 	tuple_set_u64(t, 2, es->al->machine->db_id);
-	tuple_set_u64(t, 3, es->thread->db_id);
+	tuple_set_u64(t, 3, es->al->thread->db_id);
 	tuple_set_u64(t, 4, es->comm_db_id);
 	tuple_set_u64(t, 5, es->dso_db_id);
 	tuple_set_u64(t, 6, es->sym_db_id);