updated build system

cmake/libraries/boost.cmake

@@ -69,12 +69,14 @@ if(PROJECT_ENABLE_BOOST)
       --prefix=${PROJECT_EXTERNAL_BUILD_ROOT}
       address-model=64
       architecture=${BOOST_ARCH}
-      cxxflags=-std=c++${CMAKE_CXX_STANDARD}
+      cxxstd=20
+      cxxstd-dialect=gnu
+      cxxflags=-std=gnu++${CMAKE_CXX_STANDARD}
       cxxstd=${CMAKE_CXX_STANDARD}
       define=BOOST_ASIO_HAS_STD_STRING_VIEW
       define=BOOST_SYSTEM_NO_DEPRECATED
       link=${BOOST_LINK}
-      linkflags=-std=c++${CMAKE_CXX_STANDARD}
+      linkflags=-std=gnu++${CMAKE_CXX_STANDARD}
       threading=multi
       variant=${BOOST_BUILD_TYPE_LOWER}
     )