Add running benchmarks regularly and under valgrind in travis
Add running benchmarks regularly and under valgrind in travis

bitcoin/secp256k1,bitcoin-core/secp256k1,ElementsProject/secp256k1-zkp,evoskuil/secp256k1,peterdettman/secp256k1,ElementsProject/secp256k1-zkp,bitcoin/secp256k1,afk11/secp256k1,bitcoin/secp256k1,bitcoin/secp256k1,afk11/secp256k1,evoskuil/secp256k1,evoskuil/secp256k1,bitcoin-core/secp256k1,evoskuil/secp256k1,afk11/secp256k1,bitcoin/secp256k1,afk11/secp256k1,evoskuil/secp256k1,peterdettman/secp256k1,afk11/secp256k1