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.
2f5339079b