Improve guard so it works for no eof new line

syntax/rust.vim

@@ -1,4 +1,5 @@
 if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'rust') == -1
+
 " Vim syntax file
 " Language:     Rust
 " Maintainer:   Patrick Walton <pcwalton@mozilla.com>
@@ -362,4 +363,5 @@ syn sync maxlines=500
 let b:current_syntax = "rust"
 
 " vim: set et sw=4 sts=4 ts=8:
+
 endif