Build system failure related to neurondemo.

[1uc]

During a build we run "${PROJECT_BINARY_DIR}/bin/neurondemo". This script is generated via a configure command. The script contains an optimization to not run nrnivmodl if a certain file neuron exists:

if [ ! -f "${NRNDEMO}neuron" ] ; then
	(cd "${NRNDEMO}release" ; "${NRNBIN}nrnivmodl" ; cd .. ; rm -f neuron ; touch neuron)
fi

However, this has the following downside. If we configure and build in a directory build while NEURON is broken, it will generate a special that's broken. Which is expected. However, when we fix the error. We'll not recreate the special because the file "${NRNDEMO}neuron" still exists. Hence, we're left with a broken build, even if we've fixed the issue.

I only know the workaround to delete the entire build directory and start over with configuring.

The preferred solution would be to either not optimize running nrnivmodl and see if that works; or clear the file "${NRNDEMO}neuron" if anything relevant changed during compilation.