perf threads: Remove unused dead thread list

Commit 40826c45 ("perf thread: Remove notion of dead threads")
removed dead threads but the list head wasn't removed. Remove it here.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: James Clark <james.clark@arm.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: liuwenyu <liuwenyu7@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231024222353.3024098-7-irogers@google.comSigned-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/util/machine.c

@@ -67,7 +67,6 @@ static void machine__threads_init(struct machine *machine)
 		threads->entries = RB_ROOT_CACHED;
 		init_rwsem(&threads->lock);
 		threads->nr = 0;
-		INIT_LIST_HEAD(&threads->dead);
 		threads->last_match = NULL;
 	}
 }

tools/perf/util/machine.h

@@ -35,7 +35,6 @@ struct threads {
 	struct rb_root_cached  entries;
 	struct rw_semaphore    lock;
 	unsigned int	       nr;
-	struct list_head       dead;
 	struct thread	       *last_match;
 };