Improve guard so it works for no eof new line

ftplugin/cryptol/folding.vim

@@ -1,4 +1,5 @@
 if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'cryptol') == -1
+
 " Copyright © 2013 Edward O'Callaghan. All Rights Reserved.
 
 "setlocal foldmethod=indent
@@ -45,4 +46,5 @@ function! GetPotionFold(lnum)
         return '>' . next_indent
     endif
 endfunction
+
 endif