Cleanup after runing a test.

tests/js/build.sh

@@ -7,3 +7,4 @@ touch empty.ml
 ocamlc -o empty.bytecode empty.ml
 ../../cduce --compile -I ../../stdlib main.cd
 js_of_ocaml  --extern-fs -I . --file=main.cdo --of=main.cdo.js  empty.bytecode
+rm -f empty.*