[libc++][NFC] Remove _VSTD:: when not needed.

Reviewed By: #libc, Quuxplusone

Differential Revision: https://reviews.llvm.org/D102133

NOKEYCHECK=True
GitOrigin-RevId: cfef7c918b8297ffb1d882d6b31fe68f876607db
diff --git a/include/set b/include/set
index 0a1cc06..0612dd5 100644
--- a/include/set
+++ b/include/set
@@ -1316,11 +1316,11 @@
 #if _LIBCPP_STD_VER > 11
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,iterator>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,iterator>::type
     find(const _K2& __k)                           {return __tree_.find(__k);}
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,const_iterator>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,const_iterator>::type
     find(const _K2& __k) const                     {return __tree_.find(__k);}
 #endif
 
@@ -1352,12 +1352,12 @@
 #if _LIBCPP_STD_VER > 11
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,iterator>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,iterator>::type
     lower_bound(const _K2& __k)       {return __tree_.lower_bound(__k);}
 
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,const_iterator>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,const_iterator>::type
     lower_bound(const _K2& __k) const {return __tree_.lower_bound(__k);}
 #endif
 
@@ -1370,11 +1370,11 @@
 #if _LIBCPP_STD_VER > 11
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,iterator>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,iterator>::type
     upper_bound(const _K2& __k)       {return __tree_.upper_bound(__k);}
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,const_iterator>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,const_iterator>::type
     upper_bound(const _K2& __k) const {return __tree_.upper_bound(__k);}
 #endif
 
@@ -1387,11 +1387,11 @@
 #if _LIBCPP_STD_VER > 11
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,pair<iterator,iterator>>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,pair<iterator,iterator>>::type
     equal_range(const _K2& __k)       {return __tree_.__equal_range_multi(__k);}
     template <typename _K2>
     _LIBCPP_INLINE_VISIBILITY
-    typename _VSTD::enable_if<_VSTD::__is_transparent<_Compare, _K2>::value,pair<const_iterator,const_iterator>>::type
+    typename enable_if<__is_transparent<_Compare, _K2>::value,pair<const_iterator,const_iterator>>::type
     equal_range(const _K2& __k) const {return __tree_.__equal_range_multi(__k);}
 #endif
 };