stabilize build system: depends, installer, boost/bdb fixes, cross targets groundwork

depends/x86_64-pc-linux-gnu/include/boost/hana/chain.hpp

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+/*!
+@file
+Defines `boost::hana::chain`.
+
+@copyright Louis Dionne 2013-2017
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_CHAIN_HPP
+#define BOOST_HANA_CHAIN_HPP
+
+#include <boost/hana/fwd/chain.hpp>
+
+#include <boost/hana/concept/monad.hpp>
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/dispatch.hpp>
+#include <boost/hana/flatten.hpp>
+#include <boost/hana/transform.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! @cond
+    template <typename Xs, typename F>
+    constexpr decltype(auto) chain_t::operator()(Xs&& xs, F&& f) const {
+        using M = typename hana::tag_of<Xs>::type;
+        using Chain = BOOST_HANA_DISPATCH_IF(chain_impl<M>,
+            hana::Monad<M>::value
+        );
+
+    #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
+        static_assert(hana::Monad<M>::value,
+        "hana::chain(xs, f) requires 'xs' to be a Monad");
+    #endif
+
+        return Chain::apply(static_cast<Xs&&>(xs), static_cast<F&&>(f));
+    }
+    //! @endcond
+
+    template <typename M, bool condition>
+    struct chain_impl<M, when<condition>> : default_ {
+        template <typename Xs, typename F>
+        static constexpr auto apply(Xs&& xs, F&& f) {
+            return hana::flatten(hana::transform(static_cast<Xs&&>(xs),
+                                                 static_cast<F&&>(f)));
+        }
+    };
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_CHAIN_HPP