make "metis.ML" building process slightly more robust by eliminating the need for "FILES";
instead, query the original "Makefile"
include Makefile
bin/mosml/Makefile.src:
mkdir -p `dirname $@`
echo > $@
refresh_FILES:
echo $(POLYML_SRC) | \
sed "s/src\///g" | \
sed "s/ Tptp\.s[a-z][a-z]//g" | \
sed "s/ Options\.s[a-z][a-z]//g" \
> FILES