Fixes issues which occur when building on Apple Silicon

Link to xeus-zmq
Add option to define where cxxopts folder is (Macbook unable to locate folder without)
Change header file xeus/xserver_zmq.hpp to xeus-zmq/xserver_zmq.hpp
Add #include <iostream> to include/xeus-clang-repl/xmanager.hpp otherwise errors due to use of std::cerr and others

CMakeLists.txt

@@ -89,6 +89,7 @@ set(xeus_REQUIRED_VERSION 1.0.0)
 set(cppzmq_REQUIRED_VERSION 4.3.0)
 
 find_package(xeus ${xeus_REQUIRED_VERSION} REQUIRED)
+find_package(xeus-zmq  REQUIRED) 
 find_package(cppzmq REQUIRED CONFIG)
 find_package(pugixml REQUIRED)
 
@@ -103,6 +104,11 @@ if(POLICY CMP0077)
 endif()
 
 find_package(cxxopts REQUIRED)
+
+# Added as system unable to locate cxxopts include folder on MacOS
+set(_cxxopts_install_dir ${cxxopts_install_DIR})
+include_directories( ${_cxxopts_install_dir}/include)
+
 set(Python_FIND_VIRTUALENV ONLY)
 find_package(Python COMPONENTS Interpreter Development)
 
@@ -251,7 +257,7 @@ target_include_directories(xeus-clang-repl SYSTEM
                            PUBLIC
                            $<BUILD_INTERFACE:${XEUS_CLANG-REPL_INCLUDE_DIR}>
                            $<INSTALL_INTERFACE:include>)
-target_link_libraries(xeus-clang-repl PUBLIC clangCppInterOp xeus pugixml cxxopts::cxxopts)
+target_link_libraries(xeus-clang-repl PUBLIC clangCppInterOp xeus xeus-zmq pugixml)
 
 if(APPLE)
     target_link_libraries(xeus-clang-repl PUBLIC -Wl,-w -Wl,-bind_at_load -Wl,-undefined,dynamic_lookup)

include/xeus-clang-repl/xmanager.hpp

@@ -20,6 +20,7 @@
 
 #include "nlohmann/json.hpp"
 
+#include <iostream>
 #include <map>
 #include <memory>
 #include <regex>

src/main.cpp

@@ -14,7 +14,7 @@
 
 #include "xeus/xkernel.hpp"
 #include "xeus/xkernel_configuration.hpp"
-#include "xeus/xserver_zmq.hpp"
+#include "xeus-zmq/xserver_zmq.hpp"
 
 #include "xeus-clang-repl/xeus_clang-repl_config.hpp"
 #include "xeus-clang-repl/xinterpreter.hpp"