GitLab

* Retire defines and structs previously wrapped in COMPAT_INET4 in net/if.h;
  netinet/in.h; sys/socket.h; sys/sockio.h
* Update the documentation accordingly and point to the migration page to guide
  anyone still targetting Internet 4. Document Service_InternetStatus 9.
* Add a preprocessor check to socklib.h pointing at the migration page too
* Skip generating veneers for original Internet 4 forms of accept; recvfrom;
  recvmsg; sendmsg; getpeername; getsockname
* Remove COMPAT_INET4 predefine from unixlib and inetlib Makefiles
* Consolidate two socklib Makefiles into one

Version 5.79. Tagged as 'TCPIPLibs-5_79'