Add current configure.ac

This is part of a set of WIP commits.
Some of this needs to be vetted out.
Some of it isn't needed. Some of the stuff in the soon to be committed
configs/ directory should probably be moved into autoconf, and have
--enable- or --with- options tied up.

For now, the next few commits at least get a pass1 gcc compiled.

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
Add build scripts

This commit goes along with the previous commit to add the configure.ac.
This is all WIP.
Most of this is a brain dump.
A lot of this needs to be refactored.
For now it makes a pass1 combined build.

I'm mostly making this commit so that I stop thrashing in my working
directory.

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>