itstool: rework native shebang and add class to make native itstool work

itstool was reworked in [1] to not use host's python. This patch introduced the
'-S' option for coreutils's env [2]. Unfortunately that option is relatively
young [3] and elder build-host don't support it [4].

The only way to get around this is:
* remove '-S' and -s' from native shebang
* add a class itstool.bbclass. This class depends itstool-native and creates a
  valid python3 runtime environment. Most notable in the environment is
  export PYTHONNOUSERSITE = "1"
  which does same as '-s' option: force python to avoid adding (host) user sites.

[1] http://cgit.openembedded.org/meta-openembedded/commit/meta-oe/recipes-support/itstool/itstool/0001-Don-t-use-build-time-hardcoded-python-binary-path.patch?id=e5ac325b7974a346b218d1f43b92d06f5b0dd078
[2] http://cgit.openembedded.org/meta-openembedded/tree/meta-oe/recipes-support/itstool/itstool/0001-Don-t-use-build-time-hardcoded-python-binary-path.patch
[3] 668306ed86 (diff-83d9d52b1f12ac589739ab1334ae4f30)
[4] https://errors.yoctoproject.org/Errors/Details/274743/

Signed-off-by: Andreas Müller <schnitzeltony@gmail.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/classes/itstool.bbclass

@@ -0,0 +1,5 @@
+# helper class to prepare correct environment for native itstool
+
+inherit python3native
+
+DEPENDS_append = " itstool-native"

meta-oe/recipes-support/itstool/itstool/0001-Native-Don-t-use-build-time-hardcoded-python-binary-.patch

@@ -0,0 +1,35 @@
+From 335ef14fc801c9dfbe7e5692dc71cfbe72049d2b Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Andreas=20M=C3=BCller?= <schnitzeltony@gmail.com>
+Date: Sun, 27 Oct 2019 16:38:52 +0100
+Subject: [PATCH] Native: Don't use build time hardcoded python binary path.
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This is same patch as used for target build except that we do not use the
+'-S' and '-s' option because '-S' is relatively young [1] and elder build-host
+don't support it [2]
+
+[1] https://github.com/coreutils/coreutils/commit/668306ed86c8c79b0af0db8b9c882654ebb66db2#diff-83d9d52b1f12ac589739ab1334ae4f30
+[2] https://errors.yoctoproject.org/Errors/Details/274743/
+
+Upstream-Status: Inappropriate [OE specific]
+
+Signed-off-by: Andreas Müller <schnitzeltony@gmail.com>
+---
+ itstool.in | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/itstool.in b/itstool.in
+index e64cd34..05d264f 100755
+--- a/itstool.in
++++ b/itstool.in
+@@ -1,4 +1,4 @@
+-#!@PYTHON@ -s
++#!/usr/bin/env python3
+ #
+ # Copyright (c) 2010-2018 Shaun McCance <shaunm@gnome.org>
+ #
+-- 
+2.21.0
+

meta-oe/recipes-support/itstool/itstool_2.0.6.bb

@@ -7,8 +7,10 @@ inherit autotools python3native
 
 DEPENDS = "libxml2-native"
 
-SRC_URI = "http://files.itstool.org/${BPN}/${BPN}-${PV}.tar.bz2 \
-           file://0001-Don-t-use-build-time-hardcoded-python-binary-path.patch"
+SRC_URI = "http://files.itstool.org/${BPN}/${BPN}-${PV}.tar.bz2"
+SRC_URI_append_class-native = " file://0001-Native-Don-t-use-build-time-hardcoded-python-binary-.patch"
+SRC_URI_append_class-target = " file://0002-Don-t-use-build-time-hardcoded-python-binary-path.patch"
+
 SRC_URI[md5sum] = "4306eeba4f4aee6b393d14f9c3c57ca1"
 SRC_URI[sha256sum] = "6233cc22726a9a5a83664bf67d1af79549a298c23185d926c3677afa917b92a9"