configure.ac: Don't try to dump Lisps which we couldn't find.
[runlisp] / bench /
drwxr-xr-x   ..
-rw-r--r-- 4382 Makefile.am
-rw-r--r-- 309 interp-graph.gp
-rw-r--r-- 313 lisp-graph.gp
-rwxr-xr-x 1225 massage-benchmarks
-rw-r--r-- 485 t.c
-rwxr-xr-x 179 t.lisp
-rwxr-xr-x 118 t.pl
-rwxr-xr-x 175 t.py
-rwxr-xr-x 98 t.sh
-rw-r--r-- 1894 timeit.c