Some overhauls of the modified replay code.

luprex/cpp/drv/driver-common.cpp

@@ -405,6 +405,12 @@ class Driver {
         return 0;
     }
 
+    static void replay_cb_sent_outgoing(void *vp, int chid, int ndata, const char *data) {
+        if (chid == 0) {
+            std::cerr.write(data, ndata);
+        }
+    }
+
     int drive(int argc, char *argv[]) {
         // Remove the program name from argv.
         std::string program = argv[0];
@@ -413,6 +419,7 @@ class Driver {
 
         // Load the DLL and gain access to its functions.
         call_init_engine_wrapper(&engw);
+        engw.replay_cb_sent_outgoing = replay_cb_sent_outgoing;
 
         // If argv contains "replay <filename>", do a replay,
         // and then skip everything else.