EXPERIMENT: don't flush tbs on loadvm

This should speed up fuzzing somewhat, but could also create
use-after-free bugs.

cpu.c

@@ -239,7 +239,12 @@ static int cpu_common_post_load(void *opaque, int version_id)
      * memory we've translated code from. So we must flush all TBs,
      * which will now be stale.
      */
+    /* Begin LibAFL instrumentation */
+    // Do not flush old tbs on loadvm, when fuzzing in system-mode
+#if !defined(CONFIG_USER_ONLY) && defined(AS_SHARED_LIB)
     tb_flush(cpu);
+#endif
+    /* End LibAFL instrumentation */
 
     return 0;
 }