BUG/MINOR: http: Return an error when a replace-header rule failed on the response

BUG/MINOR: http: Return an error when a replace-header rule failed on the response

Historically, http-response rules couldn't produce errors generating HTTP
responses during their evaluation. This possibility was "implicitly" added with
http-response redirect rules (51d861a4). But, at the time, replace-header rules
were kept untouched. When such a rule failed, the rules processing was just
stopped (like for an accept rule).

Conversely, when a replace-header rule fails on the request, it generates a HTTP
response (400 Bad Request).

With this patch, errors on replace-header rule are now handled in the same way
for HTTP requests and HTTP responses.

This patch should be backported in 1.7 and 1.6.