cmake HAVE_SA_LEN examples

rbfx/rbfx Source/ThirdParty/libdatachannel/deps/usrsctp/CMakeLists.txt :138 

add_definitions(-DHAVE_SA_LEN)

yanhua133/mediasoup-sfu-cpp deps/usrsctp/CMakeLists.txt :137 

add_definitions(-DHAVE_SA_LEN)