Some fixes for zbar-python build

In order to be able to build a zbar-python, we need to address
some small things. Among them, there's a requirement to use
"python3" at python's test script.

IMHO, that's a bad idea, at least upstream, as the same script also
works with python2 when using pygtk (also supported by ZBar).

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

use_python3_on_python_script.patch

@@ -0,0 +1,10 @@
+diff --git a/test/test_python.py b/test/test_python.py
+index 252c51a97256..8388d9a5aa36 100755
+--- a/test/test_python.py
++++ b/test/test_python.py
+@@ -1,4 +1,4 @@
+-#!/usr/bin/env python
++#!/usr/bin/env python3
+ #------------------------------------------------------------------------
+ #  Copyright 2019 (c) Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+ #