Signal SIMPLE-ERROR for invalid external-format arguments.

Addresses <http://abcl.org/trac/ticket/375>.

git-svn-id: http://abcl.org/svn/trunk/abcl@14735 1c010e3e-69d0-11dd-93a8-456734b0d56f
asdf-jar: fix PACKAGE to work again.

Addresses <http://abcl.org/trac/ticket/376>.

git-svn-id: http://abcl.org/svn/trunk/abcl@14736 1c010e3e-69d0-11dd-93a8-456734b0d56f