More LWG issues. Mark #2182, #2323 and #2213 as complete. Add a test for #2339, and mark that as complete. No actual changes to the libc++ code; all of these were already in place.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@202407 91177308-0d34-0410-b5e6-96231b3b80d8

test/algorithms/alg.sorting/alg.nth.element/nth_element.pass.cpp

@@ -29,6 +29,7 @@ test_one(unsigned N, unsigned M)
     std::random_shuffle(array, array+N);
     std::nth_element(array, array+M, array+N);
     assert(array[M] == M);
+    std::nth_element(array, array+N, array+N); // begin, end, end
     delete [] array;
 }
 

test/algorithms/alg.sorting/alg.nth.element/nth_element_comp.pass.cpp

@@ -42,6 +42,7 @@ test_one(unsigned N, unsigned M)
     std::random_shuffle(array, array+N);
     std::nth_element(array, array+M, array+N, std::greater<int>());
     assert(array[M] == N-M-1);
+    std::nth_element(array, array+N, array+N, std::greater<int>()); // begin, end, end
     delete [] array;
 }