Mention visibility.

--HG--
branch : HEAD
diff --git a/NEWS b/NEWS
index 2c0b511..b402823 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,7 @@
 * Added zip_discard()
 * Added ZIP_TRUNCATE for zip_open()
 * Added zip_set_compression()
+* Use gcc4's visibility __attribute__
 * More changes for Windows support
 * Additional test cases