cmake HAVE_POLLSET examples

zeromq/libzmq CMakeLists.txt :425 

check_cxx_symbol_exists(pollset_create sys/pollset.h HAVE_POLLSET)

asset-group/5ghoul-5g-nr-attacks libs/libzmq/CMakeLists.txt :393 

check_cxx_symbol_exists(pollset_create sys/pollset.h HAVE_POLLSET)