set executable bit on python scripts

tools/certs/create_self-signed.py

@@ -1,3 +1,5 @@
+#!/usr/bin/env python
+
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this 
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.

tools/valgrind_check_error.py

@@ -88,4 +88,4 @@ if log_content.isspace():
 
 # There is something fishy in the valgrind output, so error-exit
 print(log_content)
-exit(1)
+exit(1)