scripts/tags.sh: enable code completion in VIM

scripts/tags.sh: enable code completion in VIM

Vim, with the omnicppcomplete(#1) plugin, can do code completion using
information build by ctags.  Add flags needed by omnicppcomplete(#2) to
have completion on member of structure.

1: https://github.com/vim-scripts/omnicppcomplete
2: https://github.com/vim-scripts/OmniCppComplete/blob/master/doc/omnicppcomplete.txt#L93

Link: http://lkml.kernel.org/r/20160830191546.4469-1-mathieu.maret@gmail.com
Signed-off-by: Mathieu Maret <mathieu.maret@gmail.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>