consensus: guard against openssl's new strict DER checks
consensus: guard against openssl's new strict DER checks

New versions of OpenSSL will reject non-canonical DER signatures. However,
it'll happily decode them. Decode then re-encode before verification in order
to ensure that it is properly consumed.

Github-Pull: #5634
Rebased-From: 488ed32f2ada1d1dd108fc245d025c4d5f252783

bankonme/zerocash,bankonme/zerocash,marmolejo/zerocash,bankonme/zerocash,marmolejo/zerocash,marmolejo/zerocash,marmolejo/zerocash,bankonme/zerocash,bankonme/zerocash,marmolejo/zerocash