[PATCH] NEWS: Mention tcache improvements

[Wilco Dijkstra]

Update NEWS with tcache improvements.

OK for commit?

---

diff --git a/NEWS b/NEWS
index cc668344c12255220881c8c8752eef3c744123b4..7c407c2ea3da1af3dd819f58129be8b5afc606e9 100644
--- a/NEWS
+++ b/NEWS
@@ -26,6 +26,11 @@ Major new features:
   speed_t is redefined to simply be the baud rate specified as an
   unsigned int, which matches the kernel interface.
 
+* The thread-local cache in malloc (tcache) now supports caching of large
+  blocks.  This feature can be enabled by setting the tunable
+  glibc.malloc.tcache_max to a larger value (max 4194304).
+  Tcache is also significantly faster for small sizes.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The glibc.rtld.execstack now supports a compatibility mode to allow