cmake HAVE_SIN_LEN examples

yanhua133/mediasoup-sfu-cpp deps/usrsctp/CMakeLists.txt :143 

add_definitions(-DHAVE_SIN_LEN)

rbfx/rbfx Source/ThirdParty/libdatachannel/deps/usrsctp/CMakeLists.txt :144 

add_definitions(-DHAVE_SIN_LEN)