Fix issue 11267.

Compiler yields compile error within a function witch used in unevaluate
context of constexpr function because of CWG 1581 [2].

1. https://llvm.org/bugs/show_bug.cgi?id=23135
2. http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1581

include/boost/fusion/container/vector/vector.hpp

@@ -116,16 +116,6 @@ namespace boost { namespace fusion
             : vec(rhs.vec) {}
 
         template <typename Sequence>
-        // XXX:
-#if defined(__WAVE__) && defined(BOOST_FUSION_CREATE_PREPROCESSED_FILES)
-FUSION_HASH if !defined(BOOST_CLANG)
-        BOOST_CONSTEXPR
-FUSION_HASH endif
-#else
-#if !defined(BOOST_CLANG)
-        BOOST_CONSTEXPR
-#endif
-#endif
         BOOST_FUSION_GPU_ENABLED
         vector(Sequence const& rhs,
             typename boost::enable_if<traits::is_sequence<Sequence> >::type* = 0)