vim-patch:8.1.0310: file info msg with 'F' in 'shortmess'

Problem:    File info message not always suppressed with 'F' in 'shortmess'.
            (Asheq Imran)
Solution:   Save and restore msg_silent. (Christian Brabandt, closes vim/vim#3221)
2f0f871159

ref #8840
ref #9027

src/nvim/testdir/setup.vim

@@ -15,6 +15,7 @@ set nrformats+=octal
 set nohidden smarttab noautoindent noautoread complete-=i noruler noshowcmd
 set listchars=eol:$
 set fillchars=vert:\|,fold:-
+set shortmess-=F
 " Prevent Nvim log from writing to stderr.
 let $NVIM_LOG_FILE = exists($NVIM_LOG_FILE) ? $NVIM_LOG_FILE : 'Xnvim.log'