std::net: add Ipv4Addr::is_reserved()
std::net: add Ipv4Addr::is_reserved()

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust