Update pprof (from gperftools 2.0).
diff --git a/ChangeLog b/ChangeLog
index 8f6edd5..1db47d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -34,6 +34,7 @@
   - Add the --with-mangling option.
   - Add the --disable-experimental option.
   - Add the "thread.tcache.enabled" mallctl.
+  - Update pprof (from gperftools 2.0).
 
   Incompatible changes:
   - Enable stats by default.