drop even more libc functions

examples/tcp_server.zr

@@ -3,10 +3,10 @@ func main[] : I64
 
     let resp: String = mem.alloc(60000)
     while true
-        let conn: I64 = c.accept(s, 0, 0)
+        let conn: I64 = net.accept(s)
         if conn < 0
             continue
 
-        let n: I64 = c.read(conn, resp, 60000)
-        c.send(conn, resp, n, 0)
-        c.close(conn)
+        let n: I64 = net.read(conn, resp, 60000)
+        net.send(conn, resp, n)
+        net.close(conn)