[AGENT++] Identical code blocks in MibTable::commit_set_request()

[Hugo Krapf]

Hi Frank,
As I was browsing the sources, I've noticed that the if and else blocks inside
MibTable::commit_set_request() are identical.  I guess that's due to historical reasons.
But as the code stands today we end up running find() twice, since MibTable::set_value() also calls find().
I think we could safely remove the if (find(req->get_oid(ind))) { in MibTable::commit_set_request().
Best regards,
Hugo.