cmake HAVE_LINUX_NETFILTER_IPV4_H examples

shadowsocks/shadowsocks-libev cmake/configure.cmake :38 

check_include_files(linux/netfilter_ipv4.h HAVE_LINUX_NETFILTER_IPV4_H)

ShadowsocksR-Live/shadowsocksr-native cmake/configure.cmake :44 

check_include_files ( "linux/netfilter_ipv4.h" HAVE_LINUX_NETFILTER_IPV4_H )