Networking: Replace all references to the macros net_ipaddr_copy,...

Networking:  Replace all references to the macros net_ipaddr_copy, net_ipaddr_hdrcopy, net_ipaddr_cmp, net_ipaddr_hdrcmp, and net_ipaddr_maskcmp with the appropriate IPv4 or IPv6 version of the macro (such as net_ipv4addr_copy).  The goal is to support both IPv4 and IPv6 simultaneously.  This requires that the macros be distinct and not conditionally defined to one on or the other.