fix icu in boost build

cmake/libraries/boost.cmake

@@ -95,8 +95,14 @@ if(PROJECT_ENABLE_BOOST)
       endif()
 
       if(PROJECT_ENABLE_LIBBITCOIN_SYSTEM)
-        set(BOOST_CXX_STANDARD 14)
+        set(BOOST_CXX_STANDARD 17)
         set(BOOST_OPTIONS cxxflags=-Wno-enum-constexpr-conversion)
+        if (PROJECT_IS_DARWIN)
+          set(BOOST_OPTIONS   
+            ${BOOST_OPTIONS}
+            define=BOOST_NO_CXX98_FUNCTION_BASE)
+          )
+        endif()
       else()
         set(BOOST_CXX_STANDARD ${CMAKE_CXX_STANDARD})
         set(BOOST_OPTIONS define=BOOST_ASIO_HAS_STD_STRING_VIEW)