don't rely on the return value of curs_set(), as it's broken on e.g.

don't rely on the return value of curs_set(), as it's broken on e.g.
slang; instead, explicitly turn the cursor off where we need to

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@1798 35c25a1d-7b9e-4130-9fde-d3aeb78583b8