Add common debug tools to LibreELEC

It's just not needed for normal usage. These can either be compile one time and copied over or better yet just do it on a multipurpose distro.

dag There are probably no objections among the team to adding packages into the build-system to facilitate debugging when a DEBUG image is built, but they will not go into release images where 99.999999% of our userbase will never use them. I suspect you'll need to use a debug image anyway since we strip the binaries in release images.