Patches to make GNU gzip and BusyBox gzip produce identical compression results

[Kang-Che Sung]

> From 12d30559486502feec4e2821b3ab45ae6139e7aa Mon Sep 17 00:00:00 2001
> From: Daniel Edgecumbe <git at esotericnonsense.com>
> Date: Mon, 2 Sep 2019 22:09:15 +0100
> Subject: [PATCH 3/3] gzip: set default compression level to 6 when
>  CONFIG_FEATURE_GZIP_LEVELS=n
>
> With this change, GNU gzip -n and BusyBox gzip now produce identical output
> assuming that CONFIG_GZIP_FAST=2.
> ---

Excuse me, but I wonder one thing on the third patch: Why should we follow
strictly with gzip on the no-options default behavior? gzip -9 is quite fast
in modern processors, and if someone builds busybox without
CONFIG_FEATURE_GZIP_LEVELS, I think they are moke likely to stick with -9 as
default instead of -6.

The better change would be to allow the builder to choose the compression level
at build time. It would be better to resolve the debate on which level should
be the default, Otherwise, I think the third patch can be dropped.