Updated configure to add both m4 and python3, then corrected the

python preprocessor script to execute "env python3" instead of
the hard-coded non-existent directory that was on the shebang
line.

scripts/preproc.py

@@ -1,4 +1,4 @@
-#!/ef/efabless/opengalaxy/venv/bin/python3
+#!/bin/env python3
 #--------------------------------------------------------------------
 #
 # preproc.py