Added to most algos, checkhash function scans a big range
and can find multiple nonces at once if the difficulty is low.
Stop ignoring them, submit second one if found...
Clean the draft code for rc=2 implemented for blake and pentablake
btw... fix the reduced displayed hashrate when a nonce is found...
Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>