OS400 build break in tftp.c, 5th argument of Curl_os400_sendto() should be const

[jonrumsey]

I did this

Build 7.88, failed in TFTP module with following const mismatch error at line 531;

CZM0280(30) Function argument assignment between types "struct sockaddr*" and "const struct sockaddr*" is not allowed.

    senddata = sendto(state->sockfd, (void *)state->spacket.data,
                      (SEND_TYPE_ARG3)sbytes, 0,
                      &data->conn->remote_addr->sa_addr,
                      data->conn->remote_addr->addrlen);

This appears to have been uncovered by #10213.

The root cause is OS400 where in setup-os400.h, sendto() is hash defined to use Curl_os400_sendto(), however the prototype for the OS400 wrapper to deal with EBCDIC/ASCII conversions doesn't match the usual POSIX prototype of;

ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
               const struct sockaddr *dest_addr, socklen_t addrlen);

I expected the following

Clean build

curl/libcurl version

7.88

[curl -V output]

operating system

OS400 V7R5M0