Bad format specifier

[fifteenhex]

When building for i386 the format specifier when printing a ssize_t is wrong and causes the build to fail:

pjdfstest.c: In function ‘call_syscall’:
pjdfstest.c:1164:28: error: format ‘%ld’ expects argument of type ‘long int’, but argument 3 has type ‘ssize_t’ {aka ‘int’} [-Werror=format=]
 1164 |    fprintf(stderr, "read %ld bytes\n", r);
      |                          ~~^           ~
      |                            |           |
      |                            long int    ssize_t {aka int}
      |                          %d

[onlyjob]

This is definitely a problem: I'm getting the same FTBFS on Debian.