fix silly typo (#ifdef -> #ifndef) keeping nano -w from working

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@1333 35c25a1d-7b9e-4130-9fde-d3aeb78583b8

nano.c

@@ -3251,7 +3251,7 @@ int main(int argc, char *argv[])
 	case 'v':
 	    SET(VIEW_MODE);
 	    break;
-#ifdef DISABLE_WRAPPING
+#ifndef DISABLE_WRAPPING
 	case 'w':
 	    SET(NO_WRAP);
 	    break;