Building lem with Windows/Cygwin

[lastland]

Hi, I am running into some problems when trying to build lem and I do not know if these problems are Windows/Cygwin specific.

The first problem is that running make at the top-level will give me an error message saying lem is not an executable file. The problem seems to come from executing ln -sf src/main.native lem several times. This can be fixed by a few minor modifications (I can submit my changes as a PR later).

The other problem is that when running to make lib_phase_1, I will get the following message:

make -C library
make[1]: Entering directory '/home/t-yaoli/lem/library'
../lem -ocaml -outdir ../ocaml-lib -wl ign -wl_auto_import err -wl_rename err bool.lem basic_classes.lem function.lem maybe.lem num.lem tuple.lem list.lem either.lem set_helpers.lem set.lem map.lem relation.lem sorting.lem function_extra.lem assert_extra.lem list_extra.lem string.lem num_extra.lem map_extra.lem set_extra.lem maybe_extra.lem string_extra.lem word.lem show.lem show_extra.lem machine_word.lem pervasives.lem pervasives_extra.lem -auxiliary_level none -only_changed_output
Fatal error: exception Sys_error("C:\\cygwin64\\tmp\\lem_tempbd8293: Permission denied")
make[1]: *** [Makefile:24: ocaml-libs] Error 2
make[1]: Leaving directory '/home/t-yaoli/lem/library'
make: *** [Makefile:52: libs_phase_1] Error 2

I have no clue what the problem is and how to fix it. I wonder if anyone have seen this before, or have some ideas about what happened. Thanks!

PS: The C:\\cygwin64\\tmp\\lem_tempbd8293 is present in my system.