[libc++] Remove more unnecessary _VSTD:: from type names. NFCI.

Differential Revision: https://reviews.llvm.org/D102181

NOKEYCHECK=True
GitOrigin-RevId: 6491d99e330c38b33b9cb6acb19afa3a464febeb
diff --git a/include/functional b/include/functional
index 3d8138a..1eab545 100644
--- a/include/functional
+++ b/include/functional
@@ -1962,11 +1962,11 @@
 // True if _Fun can safely be held in __policy_storage.__small.
 template <typename _Fun>
 struct __use_small_storage
-    : public _VSTD::integral_constant<
+    : public integral_constant<
           bool, sizeof(_Fun) <= sizeof(__policy_storage) &&
                     _LIBCPP_ALIGNOF(_Fun) <= _LIBCPP_ALIGNOF(__policy_storage) &&
-                    _VSTD::is_trivially_copy_constructible<_Fun>::value &&
-                    _VSTD::is_trivially_destructible<_Fun>::value> {};
+                    is_trivially_copy_constructible<_Fun>::value &&
+                    is_trivially_destructible<_Fun>::value> {};
 
 // Policy contains information about how to copy, destroy, and move the
 // underlying functor. You can think of it as a vtable of sorts.
@@ -3190,8 +3190,8 @@
     operator () (_ForwardIterator2 __f, _ForwardIterator2 __l) const
     {
         return _VSTD::__search(__f, __l, __first_, __last_, __pred_,
-            typename _VSTD::iterator_traits<_ForwardIterator>::iterator_category(),
-            typename _VSTD::iterator_traits<_ForwardIterator2>::iterator_category());
+            typename iterator_traits<_ForwardIterator>::iterator_category(),
+            typename iterator_traits<_ForwardIterator2>::iterator_category());
     }
 
 private: