[neovim] Fix terminal buffer marker on Windows

Original Patch: https://github.com/junegunn/fzf/commit/a9bf29b65ec36d9caa7298aad0322fba8cb3e130

plugin/fzf.vim

@@ -35,6 +35,8 @@ else
   let s:base_dir = expand('<sfile>:h:h')
 endif
 if s:is_win
+  let s:term_marker = '&::FZF'
+
   function! s:fzf_call(fn, ...)
     let shellslash = &shellslash
     try
@@ -53,6 +55,8 @@ if s:is_win
           \ ['chcp %origchcp% > nul']
   endfunction
 else
+  let s:term_marker = ";#FZF"
+
   function! s:fzf_call(fn, ...)
     return call(a:fn, a:000)
   endfunction
@@ -681,7 +685,7 @@ function! s:execute_term(dict, command, temps) abort
     if s:present(a:dict, 'dir')
       execute 'lcd' s:escape(a:dict.dir)
     endif
-    call termopen(a:command . ';#FZF', fzf)
+    call termopen(a:command.s:term_marker, fzf)
   finally
     if s:present(a:dict, 'dir')
       lcd -