Implement --redzone-size and --core-redzone-size

* For tools replacing the malloc library (e.g. Memcheck, Helgrind, ...),
  the option --redzone-size=<number> allows to control the padding 
  blocks (redzones) added before and after each client allocated block.
  Smaller redzones decrease the memory needed by Valgrind. Bigger
  redzones increase the chance to detect blocks overrun or underrun.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12807 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/NEWS b/NEWS
index a98096b..ad79d6e 100644
--- a/NEWS
+++ b/NEWS
@@ -61,6 +61,12 @@
 
 * ==================== OTHER CHANGES ====================
 
+* For tools replacing the malloc library (e.g. Memcheck, Helgrind, ...),
+  the option --redzone-size=<number> allows to control the padding 
+  blocks (redzones) added before and after each client allocated block.
+  Smaller redzones decrease the memory needed by Valgrind. Bigger
+  redzones increase the chance to detect blocks overrun or underrun.
+
 * The C++ demangler has been updated so as to work well with C++ 
   compiled by up to at least g++ 4.6.