This PR replaces a redundant reference-to-pointer conversion in **addmultisigaddress** from *wallet/rpcwallet.cpp*. It also makes the API from *rpc/util.h* look more straightforward as **AddrToPubKey** now uses const references like other functions from there.

I am not sure why there is a ref-to-ptr conversion in addmultisignatures, so I can only speculate that this is because of "historical reasons".

The ref-to-ptr conversion happens here: https://github.com/bitcoin/bitcoin/blob/master/src/wallet/rpcwallet.cpp#L1001

There, the address of LegacyScriptPubKeyMan& is given to AddrToPubKey.

Later, in AddrToPubKey, it gets converted back to a reference, because GetKeyForDestination in rpc/util.cpp expects a const ref: https://github.com/bitcoin/bitcoin/blob/master/src/rpc/util.cpp#L140

Regards,

ninja all check check-functional