generate --event-trace output explicitly rather than in EventTraceMgr destructor

src/EventTrace.cc

@@ -958,7 +958,7 @@ EventTraceMgr::EventTraceMgr(const std::string& trace_file) {
         reporter->FatalError("can't open event trace file %s", trace_file.c_str());
 }
 
-EventTraceMgr::~EventTraceMgr() {
+void EventTraceMgr::Generate() {
     if ( events.empty() )
         return;
 

src/EventTrace.h

@@ -440,7 +440,9 @@ private:
 class EventTraceMgr {
 public:
     EventTraceMgr(const std::string& trace_file);
-    ~EventTraceMgr();
+
+    // Generates the trace upon exit.
+    void Generate();
 
     // Called at the beginning of invoking an event's handlers.
     void StartEvent(const ScriptFunc* ev, const zeek::Args* args);

src/zeek-setup.cc

@@ -399,6 +399,9 @@ static void terminate_zeek() {
 
     script_coverage_mgr.WriteStats();
 
+    if ( etm )
+        etm->Generate();
+
     delete zeekygen_mgr;
     delete packet_mgr;
     delete analyzer_mgr;