[PATCH phosphor-host-ipmid] Initial autotools support

[Stewart Smith]

OpenBMC Patches <openbmc-patches at stwcx.xyz> writes:
> This switches us over to use autotools rather than custom makefiles.
> This brings us into line with the defacto standard for building
> userspace.

I haven't converted everything yet, and I've really only started to poke
at what makes sense for the current structure of everything.

There's a magic thing we could use for plugins too, which allows in tree
and out of tree, and I haven't started using it.
See https://autotools.io/libtool/plugins.html

But first I wanted to raise the possibility of autotools and what it
kind of looks like.

We should also move to explicit exposure of symbols rather than
exporting everything.

thoughts?