Fix yet another missed -Wunused warning. Hopefully this is the last one

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@290476 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/containers/sequences/forwardlist/forwardlist.cons/size.pass.cpp

@@ -28,6 +28,9 @@ void check_allocator(unsigned n, Allocator const &alloc = Allocator())
     C d(n, alloc);
     assert(d.get_allocator() == alloc);
     assert(static_cast<std::size_t>(std::distance(d.begin(), d.end())) == n);
+#else
+    ((void)n);
+    ((void)alloc);
 #endif
 }
 
@@ -39,12 +42,14 @@ int main()
         unsigned N = 10;
         C c(N);
         unsigned n = 0;
-        for (C::const_iterator i = c.begin(), e = c.end(); i != e; ++i, ++n)
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+
+        for (C::const_iterator i = c.begin(), e = c.end(); i != e; ++i, ++n) {
+#if TEST_STD_VER >= 11
             assert(*i == T());
 #else
-            ;
+            ((void)0);
 #endif
+        }
         assert(n == N);
     }
 #if TEST_STD_VER >= 11
@@ -55,11 +60,7 @@ int main()
         C c(N);
         unsigned n = 0;
         for (C::const_iterator i = c.begin(), e = c.end(); i != e; ++i, ++n)
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
             assert(*i == T());
-#else
-            ;
-#endif
         assert(n == N);
         check_allocator<T, min_allocator<T>> ( 0 );
         check_allocator<T, min_allocator<T>> ( 3 );