Makefile's distribution and installation targets; just put it all
in the Makefile directly.
* PLUGIN/this.configure (scm_files, aux_files): Remove sections
for these.
* configure.in: Remove code that gets and substitutes scm_files and
aux_files.
* Makefile.in (scm_files, aux_files): Write out the list of files
here, where people expect to find them.