Revert "tree-wide: Always use recvmsg with MSG_CMSG_CLOEXEC"

This reverts commit d6d810fbf8.

It's apparently not OK to pass MSG_CMSG_CLOEXEC to recvmsg() of raw
sockets.

src/libsystemd-network/sd-dhcp-client.c

@@ -1582,7 +1582,7 @@ static int client_receive_message_raw(sd_event_source *s, int fd,
         iov.iov_base = packet;
         iov.iov_len = buflen;
 
-        len = recvmsg(fd, &msg, MSG_CMSG_CLOEXEC);
+        len = recvmsg(fd, &msg, 0);
         if (len < 0) {
                 log_dhcp_client(client, "could not receive message from raw "
                                 "socket: %m");

src/libsystemd-network/sd-dhcp-server.c

@@ -897,7 +897,7 @@ static int server_receive_message(sd_event_source *s, int fd,
         iov.iov_base = message;
         iov.iov_len = buflen;
 
-        len = recvmsg(fd, &msg, MSG_CMSG_CLOEXEC);
+        len = recvmsg(fd, &msg, 0);
         if (len < buflen)
                 return 0;
         else if ((size_t)len < sizeof(DHCPMessage))