JNI: Only call ecdsa_verify if its inputs parsed correctly
JNI: Only call ecdsa_verify if its inputs parsed correctly

Return 0 otherwise instead of calling it with bad parameters.

cddjr/BitcoinUnlimited,Bitcoin-com/BUcash,bitcoin/secp256k1,libbitcoin/secp256k1,Bitcoin-com/BUcash,sipa/secp256k1-zkp,BitcoinUnlimited/BitcoinUnlimited,Bitcoin-com/BUcash,afk11/secp256k1,afk11/secp256k1,pmienk/secp256k1,BTCfork/hardfork_prototype_1_mvf-bu,sipa/secp256k1-zkp,digitalbitbox/secp256k1,krzysztofwos/BitcoinUnlimited,libbitcoin/secp256k1,chfast/secp256k1,BitcoinUnlimited/BitcoinUnlimited,ElementsProject/secp256k1-zkp,evoskuil/secp256k1,BitcoinUnlimited/BitcoinUnlimited,marcusdiaz/BitcoinUnlimited,peterdettman/secp256k1,Bitcoin-com/BUcash,Justaphf/BitcoinUnlimited,evoskuil/secp256k1,libbitcoin/secp256k1,chfast/secp256k1,ElementsProject/secp256k1-zkp,digitalbitbox/secp256k1,krzysztofwos/BitcoinUnlimited,digitalbitbox/secp256k1,sipa/secp256k1-zkp,marcusdiaz/BitcoinUnlimited,digitalbitbox/secp256k1,evoskuil/secp256k1,cddjr/BitcoinUnlimited,apoelstra/secp256k1,sipa/secp256k1-zkp,libbitcoin/secp256k1,krzysztofwos/BitcoinUnlimited,apoelstra/secp256k1,marcusdiaz/BitcoinUnlimited,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,Justaphf/BitcoinUnlimited,apoelstra/secp256k1,krzysztofwos/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,pmienk/secp256k1,Justaphf/BitcoinUnlimited,voisine/secp256k1,krzysztofwos/BitcoinUnlimited,bitcoin-core/secp256k1,evoskuil/secp256k1,pmienk/secp256k1,bitcoin/secp256k1,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,evoskuil/secp256k1,Justaphf/BitcoinUnlimited,bitcoin/secp256k1,pmienk/secp256k1,chfast/secp256k1,BitcoinUnlimited/BitcoinUnlimited,afk11/secp256k1,voisine/secp256k1,marcusdiaz/BitcoinUnlimited,Bitcoin-com/BUcash,digitalbitbox/secp256k1,voisine/secp256k1,bitcoin/secp256k1,voisine/secp256k1,marcusdiaz/BitcoinUnlimited,sipa/secp256k1-zkp,libbitcoin/secp256k1,BTCfork/hardfork_prototype_1_mvf-bu,apoelstra/secp256k1,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,voisine/secp256k1,BTCfork/hardfork_prototype_1_mvf-bu,BTCfork/hardfork_prototype_1_mvf-bu,BitcoinUnlimited/BitcoinUnlimited,cddjr/BitcoinUnlimited,chfast/secp256k1,apoelstra/secp256k1,Justaphf/BitcoinUnlimited,cddjr/BitcoinUnlimited,afk11/secp256k1,Bitcoin-com/BUcash,Justaphf/BitcoinUnlimited,cddjr/BitcoinUnlimited,afk11/secp256k1,cddjr/BitcoinUnlimited,marcusdiaz/BitcoinUnlimited,pmienk/secp256k1,krzysztofwos/BitcoinUnlimited,BTCfork/hardfork_prototype_1_mvf-bu,bitcoin/secp256k1,bitcoin-core/secp256k1,peterdettman/secp256k1,BTCfork/hardfork_prototype_1_mvf-bu,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,chfast/secp256k1