visibility-decoration.

llvm-svn: 114486
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: fb100021b722163794ce8522d91a469f06bf43ce
diff --git a/include/cstddef b/include/cstddef
index a5297ec..def48bc 100644
--- a/include/cstddef
+++ b/include/cstddef
@@ -54,7 +54,7 @@
 
 #ifdef _LIBCPP_HAS_NO_NULLPTR
 
-struct nullptr_t
+struct _LIBCPP_VISIBLE nullptr_t
 {
     void* _;