reshuffle HSH_Lookup() code a bit to condense and clarify
reshuffle HSH_Lookup() code a bit to condense and clarify

With the req.grace reintroduction, we got two identical cases where
we insert a busy object: When there is no exp_oc (obviously) or
when the exp_oc does not fulfil the req.grace limit. This lead
to some code duplication.

IMHO, handling first the case where we need to insert a busy object
(with or without exp_oc) and then handling the exception that we
do not wait on a busy object if the exp_oc is in grace is cleaner.

Please note that comparing this change using diff -u does not
make much sense, I believe the simplicity of the reshuffling
change becomes clear when looking at the old and new code side-by-side

gquintard/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache