Fix unused parameters and variables

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@290459 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/thread/thread.threads/thread.thread.class/thread.thread.assign/move2.pass.cpp

@@ -58,7 +58,6 @@ int main()
     {
         G g;
         std::thread t0(g, 5, 5.5);
-        std::thread::id id = t0.get_id();
         std::thread t1;
         t0 = std::move(t1);
         assert(false);

test/std/thread/thread.threads/thread.thread.class/thread.thread.member/get_id.pass.cpp

@@ -50,7 +50,8 @@ int main()
         std::thread::id id0 = t0.get_id();
         std::thread t1;
         std::thread::id id1 = t1.get_id();
-        assert(t0.get_id() != id1);
+        assert(t0.get_id() == id0);
+        assert(id0 != id1);
         assert(t1.get_id() == std::thread::id());
         t0.join();
     }