feat(ctags): use -G option when generate tags

ref: https://github.com/SpaceVim/SpaceVim/issues/4619

bundle/gtags.vim/autoload/ctags.vim

@@ -24,12 +24,41 @@ let s:FILE = SpaceVim#api#import('file')
 
 let g:loaded_ctags = 1
 
-function! ctags#update() abort
+let s:is_u_ctags = 0
+let s:version_checked = 0
+function! s:version_std_out(id, data, event) abort
+  for line in a:data
+    if line =~# 'Universal Ctags'
+      let s:is_u_ctags = 1
+      break
+    endif
+  endfor
+endfunction
+
+function! s:version_exit(id, data, event) abort
+  if a:data ==# 0
+    let s:version_checked = 1
+    call ctags#update()
+  endif
+endfunction
+
+
+function! ctags#update(...) abort
+  if !s:version_checked
+    call s:JOB.start(['ctags', '--version'], {
+          \ 'on_stdout': funcref('s:version_std_out'),
+          \ 'on_exit': funcref('s:version_exit'),
+          \ })
+    return
+  endif
   let project_root = getcwd()
   call s:LOGGER.info('update ctags database for ' . project_root)
   let dir = s:FILE.unify_path(g:tags_cache_dir) 
         \ . s:FILE.path_to_fname(project_root)
   let cmd = ['ctags']
+  if s:is_u_ctags
+    let cmd += ['-G']
+  endif
   if !isdirectory(dir)
     call mkdir(dir, 'p')
   endif