Unbreak the packing list for this port. As the list of files to
install for the port is generated from the packing list, this
also unbreaks the port (a critical file was not installed, meaning
the mud couldn't be started). In particular:
. Don't include empty directories (these will be addressed in a
. Don't include non-existent files.
. Do include a critical header file, namely auto.h without which
the mud cannot start.