std:: quailfy the calls for cend/crend/cbegin/cend. Fixes bug 28927.

llvm-svn: 278282
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 7725546a3263b81a792895aaa348d310263118ad
diff --git a/include/iterator b/include/iterator
index abd142e..0caabbb 100644
--- a/include/iterator
+++ b/include/iterator
@@ -1632,16 +1632,16 @@
 
 template <class _Cp>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-auto cbegin(const _Cp& __c) -> decltype(begin(__c))
+auto cbegin(const _Cp& __c) -> decltype(_VSTD::begin(__c))
 {
-    return begin(__c);
+    return _VSTD::begin(__c);
 }
 
 template <class _Cp>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-auto cend(const _Cp& __c) -> decltype(end(__c))
+auto cend(const _Cp& __c) -> decltype(_VSTD::end(__c))
 {
-    return end(__c);
+    return _VSTD::end(__c);
 }
 
 template <class _Cp>
@@ -1674,16 +1674,16 @@
 
 template <class _Cp>
 inline _LIBCPP_INLINE_VISIBILITY
-auto crbegin(const _Cp& __c) -> decltype(rbegin(__c))
+auto crbegin(const _Cp& __c) -> decltype(_VSTD::rbegin(__c))
 {
-    return rbegin(__c);
+    return _VSTD::rbegin(__c);
 }
 
 template <class _Cp>
 inline _LIBCPP_INLINE_VISIBILITY
-auto crend(const _Cp& __c) -> decltype(rend(__c))
+auto crend(const _Cp& __c) -> decltype(_VSTD::rend(__c))
 {
-    return rend(__c);
+    return _VSTD::rend(__c);
 }
 
 #endif