use c++ 20 and limit ninja

CMakeLists.txt

@@ -9,7 +9,7 @@ endif()
 MESSAGE("CMAKE_BUILD_TYPE = ${CMAKE_BUILD_TYPE}\nWEBRTCROOT = ${WEBRTCROOT}\nWEBRTCDESKTOPCAPTURE= ${WEBRTCDESKTOPCAPTURE}\nCMAKE_CXX_COMPILER_ID=${CMAKE_CXX_COMPILER_ID}")
 
 set (CMAKE_POSITION_INDEPENDENT_CODE ON)
-set (CMAKE_CXX_STANDARD 17)
+set (CMAKE_CXX_STANDARD 20)
 set (CMAKE_CXX_EXTENSIONS OFF)
 
 # build version identifier
@@ -125,7 +125,7 @@ if (NOT EXISTS ${WEBRTCOBJS}/${CMAKE_STATIC_LIBRARY_PREFIX}webrtc${CMAKE_STATIC_
   EXECUTE_PROCESS(WORKING_DIRECTORY ${WEBRTCROOT}/src/out/${CMAKE_BUILD_TYPE} COMMAND ${SHELLCOMMAND} gn gen .)
 
   SET(NINJA_TARGET webrtc rtc_json jsoncpp builtin_video_decoder_factory builtin_video_encoder_factory peerconnection p2p_server_utils task_queue default_task_queue_factory)
-  EXECUTE_PROCESS(WORKING_DIRECTORY ${WEBRTCROOT}/src/out/${CMAKE_BUILD_TYPE} COMMAND ninja ${NINJA_TARGET})
+  EXECUTE_PROCESS(WORKING_DIRECTORY ${WEBRTCROOT}/src/out/${CMAKE_BUILD_TYPE} COMMAND ninja -l10 ${NINJA_TARGET})
 endif()