Make Boost::system optional in azmqConfig.cmake

Author: jp-pino

azmqConfig.cmake

@@ -1,6 +1,11 @@
 include(CMakeFindDependencyMacro)
-find_package(Boost 1.68 COMPONENTS system date_time thread chrono random REQUIRED)
+find_package(Boost 1.68 COMPONENTS date_time thread chrono random REQUIRED)
+find_package(Boost 1.68 COMPONENTS system)
+if (NOT Boost_SYSTEM_FOUND)
+    message(WARNING "Boost::system not found")
+endif()
+
 include(${CMAKE_CURRENT_LIST_DIR}/FindAzmqLibzmq.cmake)
 set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
 find_package(Threads REQUIRED)
-include("${CMAKE_CURRENT_LIST_DIR}/azmqTargets.cmake")
+include("${CMAKE_CURRENT_LIST_DIR}/azmqTargets.cmake")