BUG/MINOR: fix forcing fastinter in "on-error"

health_adjust() should requeue the task after changing its expire timer.

I noticed it on devel servers without load. We have long inter (10 seconds)
and short fasinter (100ms). But according to webserver logs, after a failed
request next check request was called with same 10s interval.

This patch should probably be backported to 1.4 which has the same feature.
MINOR: http: compute response time before processing headers

At the moment, HTTP response time is computed after response headers are
processed. This can misleadingly assign to the server some heavy local
processing (eg: regex), and also prevents response headers from passing
information related to the response time (which can sometimes be useful
for stats).

Let's retrieve the reponse time before processing the headers instead.

Note that in order to remain compatible with what was previously done,
we disable the response time when we get a 502 or any bad response. This
should probably be changed in 1.6 since it does not make sense anymore
to lose this information.
Merge branch 'master' of http://git.1wt.eu/git/haproxy