_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
diff --git a/include/__mutex_base b/include/__mutex_base
index 6f98d2e..9e472fc 100644
--- a/include/__mutex_base
+++ b/include/__mutex_base
@@ -190,8 +190,8 @@
     _LIBCPP_INLINE_VISIBILITY
     void swap(unique_lock& __u)
     {
-        _STD::swap(__m_, __u.__m_);
-        _STD::swap(__owns_, __u.__owns_);
+        _VSTD::swap(__m_, __u.__m_);
+        _VSTD::swap(__owns_, __u.__owns_);
     }
     _LIBCPP_INLINE_VISIBILITY
     mutex_type* release()
@@ -429,7 +429,7 @@
                              _Predicate __pred)
 {
     return wait_until(__lk, chrono::steady_clock::now() + __d,
-                      _STD::move(__pred));
+                      _VSTD::move(__pred));
 }
 
 _LIBCPP_END_NAMESPACE_STD