Fails with list_mk_conj if the list is empty or if the list has more than
one element, one or more of which are not of type `:bool`.
EXAMPLE
# list_mk_conj [`T`;`F`;`T`];;
val it : term = `T /\ F /\ T`
# list_mk_conj [`T`;`1`;`F`];;
Exception: Failure "mk_binary".
# list_mk_conj [`1`];;
val it : term = `1`