BUG/MINOR: http: block rules forgot to increment the session's request counter

BUG/MINOR: http: block rules forgot to increment the session's request counter

The session's backend request counters were incremented after the block
rules while these rules could increment the session's error counters,
meaning that we could have more errors than requests reported in a stick
table! Commit 5d5b5d8 ("MEDIUM: proto_tcp: add support for tracking L7
information") is the most responsible for this.

This bug is 1.5-specific and does not need any backport.