Add 'is_always_equal' tests for scoped_allocator. Found that I had typed '||' where I meant '&&' in the code; fixed that, too

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@238931 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/scoped_allocator b/include/scoped_allocator
index 22e3a30..cd4987a 100644
--- a/include/scoped_allocator
+++ b/include/scoped_allocator
@@ -183,7 +183,7 @@
 struct __get_is_always_equal<_A0, _Allocs...>
 {
     static const bool value =
-        allocator_traits<_A0>::is_always_equal::value ||
+        allocator_traits<_A0>::is_always_equal::value &&
         __get_is_always_equal<_Allocs...>::value;
 };