Subzero: Improve the output with the --timing-focus=xxx option.

src/IceTimerTree.cpp

Index: src/IceTimerTree.cpp
diff --git a/src/IceTimerTree.cpp b/src/IceTimerTree.cpp
index 0cd73dce2aa39e01acdc504e69bfd36f65a69907..618f37f931458fd72df4672bb3f12c79b78dae9e 100644
--- a/src/IceTimerTree.cpp
+++ b/src/IceTimerTree.cpp
@@ -97,6 +97,15 @@ void TimerStack::update() {
   }
 }
 
+void TimerStack::reset() {
+  StateChangeCount = 0;
+  FirstTimestamp = LastTimestamp = timestamp();
+  LeafTimes.assign(LeafTimes.size(), 0);
+  for (TimerTreeNode &Node : Nodes) {
+    Node.Time = 0;
+  }
+}
+
 namespace {
 
 typedef std::multimap<double, IceString> DumpMapType;