_STD -> _VSTD to avoid macro clash on windows

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@134190 91177308-0d34-0410-b5e6-96231b3b80d8

include/ext/hash_set

diff --git a/include/ext/hash_set b/include/ext/hash_set
index 1f8712b..e205db8 100644
--- a/include/ext/hash_set
+++ b/include/ext/hash_set
@@ -627,9 +627,9 @@
     {
         _EqRng __xeq = __x.equal_range(*__i);
         _EqRng __yeq = __y.equal_range(*__i);
-        if (_STD::distance(__xeq.first, __xeq.second) !=
-            _STD::distance(__yeq.first, __yeq.second) ||
-                  !_STD::is_permutation(__xeq.first, __xeq.second, __yeq.first))
+        if (_VSTD::distance(__xeq.first, __xeq.second) !=
+            _VSTD::distance(__yeq.first, __yeq.second) ||
+                  !_VSTD::is_permutation(__xeq.first, __xeq.second, __yeq.first))
             return false;
         __i = __xeq.second;
     }