Add protection from min/max macros

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@145407 91177308-0d34-0410-b5e6-96231b3b80d8

include/fstream

diff --git a/include/fstream b/include/fstream
index b6a2ab0..4456c01 100644
--- a/include/fstream
+++ b/include/fstream
@@ -171,6 +171,8 @@
 #include <__locale>
 #include <cstdio>
 
+#include <__undef_min_max>
+
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif