Makefile.am: Don't pass a variable twice
Makefile.am: Don't pass a variable twice

bitcoin/secp256k1,bitcoin/secp256k1,bitcoin-core/secp256k1,bitcoin-core/secp256k1,peterdettman/secp256k1,ElementsProject/secp256k1-zkp,bitcoin/secp256k1,bitcoin/secp256k1,bitcoin/secp256k1,peterdettman/secp256k1,ElementsProject/secp256k1-zkp