socket option on a new TCP socket. The HAVE_SOCKET_KEEPALIVE macro is obsolete. r=srinivas@netscape.com. Modified files: _beos.h, _os2.h, _unixos.h, _win16.h, _win95.h, _winnt.h, prsocket.c, and ptio.c. git-svn-id: svn://10.0.0.236/trunk@51902 18797224-902f-48f8-a5cc-f745e15eee43