Add bug number

[Marek Polacek]

Seems like Andreas forgot to update NEWS in 850fb0.

--- libc/NEWS.mp	2011-12-08 17:52:34.116675188 +0100
+++ libc/NEWS	2011-12-08 17:53:18.513735405 +0100
@@ -12,7 +12,7 @@ Version 2.15
   6779, 6783, 9696, 10103, 10709, 11589, 12403, 12847, 12868, 12852, 12874,
   12885, 12892, 12907, 12922, 12935, 13007, 13021, 13067, 13068, 13090,
   13092, 13114, 13118, 13123, 13134, 13138, 13147, 13150, 13179, 13192,
-  13268, 13276, 13291, 13335, 13337, 13344, 13358, 13367
+  13268, 13276, 13291, 13335, 13337, 13344, 13358, 13367, 13472
 
 * New program pldd to list loaded object of a process
   Implemented by Ulrich Drepper.

	Marek