Remove -async-proofs{,-tac}-j from _CoqProject
Remove -async-proofs{,-tac}-j from _CoqProject

CoqIDE.app is actually accepting those arguments, but -R coqbuild Fscq
does not work for some reason specifically with the Mac app.

mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl