Improve guard so it works for no eof new line

ftplugin/kotlin.vim

@@ -1,7 +1,9 @@
 if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'kotlin') == -1
+
 if exists('b:did_ftplugin') | finish | endif
 let b:did_ftplugin = 1
 
 setlocal comments=://
 setlocal commentstring=//\ %s
+
 endif