BUG/MEDIUM: ssl/cli: fix yielding in show_cafile_detail

BUG/MEDIUM: ssl/cli: fix yielding in show_cafile_detail

HAProxy crashes when "show ssl ca-file" is being called on a ca-file
which contains a lot of certificates. (127 in our test with
/etc/ssl/certs/ca-certificates.crt).

The root cause is the fonction does not yield when there is no available
space when writing the details, and we could write a lot.

To fix the issue, we try to put the data with ci_putchk() after every
show_cert_detail() and we yield if the ci_putchk() fails.

This patch also cleans up a little bit the code:

- the end label is now a real end with a return 1;
- i0 is used instead of (long)p1
- the ID is stored upon yield