Move BufWrite autocmd to ftplugin

Move the autocommand into the ftplugin, making it buffer local.

Author: gpanders

ftplugin/zig.vim

@@ -50,6 +50,13 @@ endif
 let b:undo_ftplugin =
     \ 'setl isk< et< ts< sts< sw< fo< sua< mp< com< cms< inex< inc< pa<'
 
+augroup vim-zig
+    autocmd! * <buffer>
+    autocmd BufWritePre <buffer> if get(g:, 'zig_fmt_autosave', 1) | call zig#fmt#Format() | endif
+augroup END
+
+let b:undo_ftplugin .= '|au! vim-zig * <buffer>'
+
 let &cpo = s:cpo_orig
 unlet s:cpo_orig
 " vim: tabstop=8 shiftwidth=4 softtabstop=4 expandtab