Dimitry Andric:  many visibility fixes.  Howard:  Much appreciated.  Can you send me a patch to CREDITS.TXT?

llvm-svn: 163862
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: aeb85680fb688e96ba2d2fc7703ae6e57cc44097
diff --git a/include/istream b/include/istream
index b48f856..72b2004 100644
--- a/include/istream
+++ b/include/istream
@@ -194,7 +194,7 @@
 public:
 
     // 27.7.1.1.3 Prefix/suffix:
-    class sentry;
+    class _LIBCPP_VISIBLE sentry;
 
     // 27.7.1.2 Formatted input:
     basic_istream& operator>>(basic_istream& (*__pf)(basic_istream&));