BUG/MINOR: ssl: can't use crt-store some certificates in ssl-f-use

BUG/MINOR: ssl: can't use crt-store some certificates in ssl-f-use

When declaring a certificate via the crt-store section, this certificate
can then be used 2 ways in a crt-list:
- only by using its name, without any crt-store options
- or by using the exact set of crt-list option that was defined in the
  crt-store

Since ssl-f-use is generating a crt-list, this is suppose to behave the
same. To achieve this, ckch_conf_parse() will parse the keywords related
to the ckch_conf on the ssl-f-use line and use ckch_conf_cmp() to
compare it to the previous declaration from the crt-store. This
comparaison is only done when any ckch_conf keyword are present.

However, ckch_conf_parse() was done for the crt-list, and the crt-list
does not use the "crt" parameter to declare the name of the certificate,
since it's the first element of the line. So when used with ssl-f-use,
ckch_conf_parse() will always see a "crt" keyword which is a ckch_conf
one, and consider that it will always need to have the exact same set of
paremeters when using the same crt in a crt-store and an ssl-f-use line.

So a simple configuration like this:

   crt-store web
     load crt "foo.com.crt" key "foo.com.key" alias "foo"

   frontend mysite
     bind :443 ssl
     ssl-f-use crt "@web/foo" ssl-min-ver TLSv1.2

Would lead to an error like this:

    config : '@web/foo' in crt-list '(null)' line 0, is already defined with incompatible parameters:
    - different parameter 'key' : previously 'foo.com.key' vs '(null)'

In order to fix the issue, this patch parses the "crt" parameter itself
for ssl-f-use instead of using ckch_conf_parse(), so the keyword would
never be considered as a ckch_conf keyword to compare.

This patch also take care of setting the CKCH_CONF_SET_CRTLIST flag only
if a ckch_conf keyword was found. This flag is used by ckch_conf_cmp()
to know if it has to compare or not.

No backport needed.