cmake HAVE_SIN6_LEN examples

yanhua133/mediasoup-sfu-cpp deps/usrsctp/CMakeLists.txt :149 

add_definitions(-DHAVE_SIN6_LEN)

rbfx/rbfx Source/ThirdParty/libdatachannel/deps/usrsctp/CMakeLists.txt :150 

add_definitions(-DHAVE_SIN6_LEN)