This patch corrects ambiguous partial specializations of
typelist::detail::append_. Previously, neither append_<chain<Hd, Tl>,
Typelist_Chain> nor append_<Typelist_Chain, null_type> was a better
match for append_<chain<Hd, Tl>, null_type>.
2019-02-22 Tom Honermann <tom@honermann.net>
* include/ext/typelist.h: Constrain a partial specialization of
typelist::detail::append_ to only match chain<T1,T2>.
From-SVN: r269088
