Merge pull request #8448 from smlng/fix_auto_tests_1801

tests: fix some minor issues with auto tests scripts

tests/lwip/tests/01-run.py

-#! /usr/bin/env python
+#! /usr/bin/env python3
 # -*- coding: utf-8 -*-
 # vim:fenc=utf-8
 #

tests/thread_msg_block_w_queue/Makefile

@@ -7,6 +7,4 @@ DISABLE_MODULE += auto_init
 include $(RIOTBASE)/Makefile.include
 
 test:
-# `testrunner` calls `make term` recursively, results in duplicated `TERMFLAGS`.
-# So clears `TERMFLAGS` before run.
-	TERMFLAGS= tests/01-run.py
+	tests/01-run.py

tests/thread_msg_block_wo_queue/Makefile

@@ -7,6 +7,4 @@ DISABLE_MODULE += auto_init
 include $(RIOTBASE)/Makefile.include
 
 test:
-# `testrunner` calls `make term` recursively, results in duplicated `TERMFLAGS`.
-# So clears `TERMFLAGS` before run.
-	TERMFLAGS= tests/01-run.py
+	tests/01-run.py

tests/xtimer_usleep/tests/01-run.py

-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 # vim:fenc=utf-8
 

tests/xtimer_usleep_short/tests/01-run.py

-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (C) 2017 Michel Rottleuthner <michel.rottleuthner@haw-hamburg.de>
 #