build: (fixes #1197) Silence Boost find_package warning message

build-support/macros-and-definitions.cmake

@@ -850,12 +850,14 @@ macro(process_options)
     cmake_policy(SET CMP0167 NEW)
   endif()
   mark_as_advanced(Boost_INCLUDE_DIR)
-  find_package(Boost)
+  find_package(Boost QUIET)
   if(${Boost_FOUND})
     if(NOT ${NS3_FORCE_LOCAL_DEPENDENCIES})
       include_directories(${Boost_INCLUDE_DIRS})
     endif()
     set(CMAKE_REQUIRED_INCLUDES ${Boost_INCLUDE_DIRS})
+  else()
+    message(HIGHLIGHTED_STATUS "Boost was not found")
   endif()
 
   set(GSL_FOUND FALSE)