Add limits compatibility header

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Use BABELTRACE_HOST_NAME_MAX in test_ctf_writer.c

This fixes the build on FreeBSD.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Conflicts:
	tests/lib/test_ctf_writer.c