lj_trace.c: unpatch blacklisted bytecodes when flushing traces

The blacklist is cleared by going through all prototype objects on the
heap marked to contain patched bytecodes and revert all instances of
IFUNCF, IFORL, IITERL and ILOOP.

(cherry picked from commit 8beb311)

src/lj_trace.c

@@ -251,6 +251,15 @@ int lj_trace_flushall(lua_State *L)
   }
   J->cur.traceno = 0;
   J->freetrace = 0;
+  /* Unpatch blacklisted byte codes. */
+  GCRef *p = &(G(L)->gc.root);
+  GCobj *o;
+  while ((o = gcref(*p)) != NULL) {
+    if (o->gch.gct == ~LJ_TPROTO) {
+      lj_trace_reenableproto(gco2pt(o));
+    }
+    p = &o->gch.nextgc;
+  }
   /* Clear penalty cache. */
   memset(J->penalty, 0, sizeof(J->penalty));
   /* Free the whole machine code and invalidate all exit stub groups. */