xeus-zmq needs CXX standard

[barracuda156]

--->  Configuring xeus-zmq
Executing:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_xeus-zmq/xeus-zmq/work/build" && /opt/local/bin/cmake -G "CodeBlocks - Unix Makefiles" -DCMAKE_BUILD_TYPE=MacPorts -DCMAKE_INSTALL_PREFIX="/opt/local" -DCMAKE_INSTALL_NAME_DIR="/opt/local/lib" -DCMAKE_SYSTEM_PREFIX_PATH="/opt/local;/usr" -DCMAKE_C_COMPILER="$CC" -DCMAKE_CXX_COMPILER="$CXX" -DCMAKE_OBJC_COMPILER="$CC" -DCMAKE_OBJCXX_COMPILER="$CXX" -DCMAKE_POLICY_DEFAULT_CMP0025=NEW -DCMAKE_POLICY_DEFAULT_CMP0060=NEW -DCMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_COLOR_MAKEFILE=ON -DCMAKE_FIND_FRAMEWORK=LAST -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DCMAKE_MAKE_PROGRAM=/usr/bin/make -DCMAKE_MODULE_PATH="/opt/local/share/cmake/Modules" -DCMAKE_PREFIX_PATH="/opt/local/share/cmake/Modules" -DCMAKE_BUILD_WITH_INSTALL_RPATH:BOOL=ON -DCMAKE_INSTALL_RPATH="/opt/local/lib" -Wno-dev -DOPENSSL_ROOT_DIR=/opt/local/libexec/openssl3 -DOPENSSL_INCLUDE_DIR=/opt/local/libexec/openssl3/include -DWITH_SSL=/opt/local/libexec/openssl3 -DCMAKE_OSX_ARCHITECTURES="ppc" -DCMAKE_OSX_DEPLOYMENT_TARGET="10.6" -DCMAKE_OSX_SYSROOT="/" /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_xeus-zmq/xeus-zmq/work/xeus-zmq-1.0.2 
-- The C compiler identification is GNU 4.2.1
-- The CXX compiler identification is GNU 4.2.1
-- Checking whether C compiler has -isysroot
-- Checking whether C compiler has -isysroot - yes
-- Checking whether C compiler supports OSX deployment target flag
-- Checking whether C compiler supports OSX deployment target flag - yes
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/gcc-4.2 - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Checking whether CXX compiler has -isysroot
-- Checking whether CXX compiler has -isysroot - yes
-- Checking whether CXX compiler supports OSX deployment target flag
-- Checking whether CXX compiler supports OSX deployment target flag - yes
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/g++-4.2 - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- xeus version: v1.0.2
-- xeus binary version: v1.0.0
-- XEUS_ZMQ_DISABLE_ARCH_NATIVE:        
-- XEUS_ZMQ_BUILD_SHARED_LIBS:          ON
-- XEUS_ZMQ_BUILD_STATIC_LIBS:          ON
-- XEUS_ZMQ_STATIC_DEPENDENCIES:        OFF
-- XEUS_ZMQ_BUILD_TESTS:                OFF
-- Found nlohmann_json: /opt/local/share/cmake/nlohmann_json/nlohmann_jsonConfig.cmake (found suitable version "3.11.2", minimum required is "3.2.0") 
-- Found OpenSSL: /opt/local/lib/libcrypto.dylib (found version "3.0.7")  
CMake Error at CMakeLists.txt:260 (target_compile_features):
  target_compile_features The compiler feature "cxx_std_14" is not known to
  CXX compiler

  "GNU"

  version 4.2.1.

[barracuda156]

In 2e099e14bfe6142dde77829a53e74894ee9c91a8/macports-ports (master):

xeus-zmq: set cxx_standard 2014, fix build on <10.7
Fixes: #66817
Signed-off-by: Sergey Fedorov <vital.had@…>