Disable all of Tier 2 only if PYTHON_UOPS_OPTIMIZE=0

Author: gvanrossum

Python/optimizer.c

@@ -1008,8 +1008,8 @@ uop_optimize(
         return err;
     }
     OPT_STAT_INC(traces_created);
-    char *uop_optimize = Py_GETENV("PYTHONUOPSOPTIMIZE");
-    if (uop_optimize == NULL || *uop_optimize > '0') {
+    char *env_var = Py_GETENV("PYTHON_UOPS_OPTIMIZE");
+    if (env_var == NULL || *env_var == '\0' || *env_var > '0') {
         err = _Py_uop_analyze_and_optimize(frame, buffer,
                                            UOP_MAX_TRACE_LENGTH,
                                            curr_stackentries, &dependencies);