recovered structural equality from 9d97bd3c086a, otherwise update_perspective might be issued over and over again, canceling a pending/slow execution;
include Makefile
bin/mosml/Makefile.src:
mkdir -p `dirname $@`
echo > $@
refresh_FILES:
echo $(POLYML_SRC) | \
sed "s/src\/PortablePolyml/PortableIsabelle/g" | \
sed "s/ src\/Tptp\.s[a-z][a-z]//g" | \
sed "s/ src\/Options\.s[a-z][a-z]//g" \
> FILES