[vim] Fix height calculation

Fix #1418

e.g.
  call fzf#run({'source': [1, 2, 3], 'down': '~50%', 'options': "--border --header $'1\n2'"})

plugin/fzf.vim

@@ -642,9 +642,11 @@ function! s:calc_size(max, val, dict)
   endif
 
   let opts = $FZF_DEFAULT_OPTS.' '.s:evaluate_opts(get(a:dict, 'options', ''))
-  let margin = stridx(opts, '--inline-info') > stridx(opts, '--no-inline-info') ? 1 : 2
+  let margin = match(opts, '--inline-info\|--info[^-]\{-}inline') > match(opts, '--no-inline-info\|--info[^-]\{-}\(default\|hidden\)') ? 1 : 2
   let margin += stridx(opts, '--border') > stridx(opts, '--no-border') ? 2 : 0
-  let margin += stridx(opts, '--header') > stridx(opts, '--no-header')
+  if stridx(opts, '--header') > stridx(opts, '--no-header')
+    let margin += len(split(opts, "\n"))
+  endif
   return srcsz >= 0 ? min([srcsz + margin, size]) : size
 endfunction