/usr/share/vim/addons/plugin/ is in vim-syntastic 3.5.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/vim/addons/plugin/syntastic/
/usr/share/vim/addons/plugin/syntastic.vim
/usr/share/vim/addons/plugin/syntastic/autoloclist.vim
/usr/share/vim/addons/plugin/syntastic/balloons.vim
/usr/share/vim/addons/plugin/syntastic/checker.vim
/usr/share/vim/addons/plugin/syntastic/cursor.vim
/usr/share/vim/addons/plugin/syntastic/highlighting.vim
/usr/share/vim/addons/plugin/syntastic/loclist.vim
/usr/share/vim/addons/plugin/syntastic/modemap.vim
/usr/share/vim/addons/plugin/syntastic/notifiers.vim
/usr/share/vim/addons/plugin/syntastic/registry.vim
/usr/share/vim/addons/plugin/syntastic/signs.vim