Fix __wrap_iter in debug mode and apply _NOEXCEPT_DEBUG to it

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@290654 91177308-0d34-0410-b5e6-96231b3b80d8

include/algorithm

@@ -1681,6 +1681,20 @@ __unwrap_iter(__wrap_iter<_Tp*> __i)
     return __i.base();
 }
 
+#else
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_trivially_copy_assignable<_Tp>::value,
+    __wrap_iter<_Tp*>
+>::type
+__unwrap_iter(__wrap_iter<_Tp*> __i)
+{
+    return __i;
+}
+
 #endif  // _LIBCPP_DEBUG_LEVEL < 2
 
 template <class _InputIterator, class _OutputIterator>