[BUG]: Restore clearing t->logs.bytes

[BUG]: Restore clearing t->logs.bytes

Commit 8b3977ffe36190e45fb974bf813bfbd935ac99a1 removed "t->logs.bytes_in = 0;"
but instead it should change it into "t->logs.bytes_out = 0;" as since
583bc966064e248771e75c253dddec7351afd8a2 counters are incremented not set.

It should be incremented in session_process_counters while sending data to a
client:
        bytes = s->rep->total - s->logs.bytes_out;
        s->logs.bytes_out = s->rep->total;

However, if we increment (set) s->logs.bytes_out while processing
"logasap", statistics get wrong values added for headers: 0 or even
negative if haproxy adds some headers itself.

To test it, please enable logasap and download one empty file and look at
stats. Without my fix information available on that page are invalid, for
example:

# pxname,svname,qcur,qmax,scur,smax,slim,stot,bin,bout,dreq,dresp,ereq,econ,eresp,wretr,wredis,status,weight,act,bck,chkfail,chkdown,lastchg,downtime,qlimit,pid,iid,sid,throttle,lbtot,
www,b,0,0,0,1,,1,24,-92,,0,,0,0,0,,UP,1,1,0,0,0,3121,0,,1,2,1,,1,
www,BACKEND,0,0,0,1,0,1,24,-92,0,0,,0,0,0,0,UP,1,1,0,,0,3121,0,,1,2,0,,1,