Build fixes

[snogge]

1. There was a missing , in an AS_CASE in configure.ac
2. scripts/Makefile.am in did not handle separated source and build directories. Replace the local rules with Automake declarations. This will create the required install, uninstall, and clean operations.
3. Update the m4-files copied from autoconf-archive. Just because I could.

[snogge]

There is a problem with the use of ax_lua.m4. It does not support cross compilation.
I did a workaround that I will eventually contribute to meta-virtualization where I used pkg-config to read lua version and such. But the lua.pc file is an OpenEmbedded thing and is not part of the regular lua releases.
Not sure how to handle it more generally.

[garlick]

This looks good - thanks! I'll merge once CI finishes.

I don't have any great ideas on the lua question....