If --enable-suexec is specified, then we need to build suexec automatically. This bit me multiple times last night as I was trying to setup apache.org. I would make a change to the configuration, run make; make install, and it would fail. The problem was that suexec wasn't getting re-compiled ever, so my changes weren't getting picked up. This solves that problem, by making sure that suexec gets compiled if it was specified on the configure line.