MINOR: proxy/http-ana: Add support of extra attributes for the cookie directive

It is now possible to insert any attribute when a cookie is inserted by
HAProxy. Any value may be set, no check is performed except the syntax validity
(CTRL chars and ';' are forbidden). For instance, it may be used to add the
SameSite attribute:

    cookie SRV insert attr "SameSite=Strict"

The attr option may be repeated to add several attributes.

This patch should fix the issue #361.

(cherry picked from commit 2f5339079b884ac8bdde166add1879ebfd9e433b)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit fac50825151ac2abc6b71343e3ffa6e0dc06c53d)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 6aa0de1..9b06955 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -339,6 +339,7 @@
 	int  cookie_len;			/* strlen(cookie_name), computed only once */
 	char *cookie_domain;			/* domain used to insert the cookie */
 	char *cookie_name;			/* name of the cookie to look for */
+	char *cookie_attrs;                     /* list of attributes to add to the cookie */
 	char *dyncookie_key;			/* Secret key used to generate dynamic persistent cookies */
 	unsigned int cookie_maxidle;		/* max idle time for this cookie */
 	unsigned int cookie_maxlife;		/* max life time for this cookie */