The CONTRIBUTING.md requests an (or multiple) SPDX identifier for GPL
licenses. But a lot of packages did use a different, non-SPDX style with a
"+" at the end instead of "-or-later".

Signed-off-by: Sven Eckelmann <sven@narfation.org>

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

Rework package recipe:

- use PKG_SOURCE_DATE
- use xz compression
- add hash
- get rid of PKG_SOURCE_SUBDIR/PKG_BUILD_DIR

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>

Don't group any utilities but just list them all as they are.

Fixes:
https://github.com/openwrt/packages/issues/3695

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>

Signed-off-by: Anton Glukhov <anton.a.glukhov@gmail.com>

[Minor fixes]
Signed-off-by: Michael Heimpold <mhei@heimpold.de>