`tests/exception/t9657` fails on OpenBSD

[euantorano]

The test tests/exception/t9657 fails on OpenBSD, as the test exits with exit code 0.

The following C file also exits without any output and a status code of 0:

#include <stdio.h>
#include <string.h>

int main(int argc, char** argv)
{
        char* msg = "exception!";
        int ret = fclose(stdout);

        if (ret != 0) {
                perror("fclose error");
                return 1;
        }

        fwrite(msg, 1, 10, stdout);
        ret = ferror(stdout);

        if (ret != 0) {
                char* errmsg = strerror(ret);
                fprintf(stderr, "fwrite error %d: %s", ret, errmsg);
                return 1;
        }

        return 0;
}

We should probably disable this test for OpenBSD, though it seems odd that this isn't an error in OpenBSD...

[brynet]

Calling fwrite/ferror after fclose is undefined behaviour. If that's what the test is boiling down to, then the test is bogus.

After the call to fclose(), any use of stream results in undefined behavior.

https://pubs.opengroup.org/onlinepubs/9699919799/functions/fclose.html