master
Update secp256k1 subtree to latest master
Update secp256k1 subtree to latest upstream
Update secp256k1 subtree to latest upstream master
Merge commit 'd48555b36ac512161b81f9b6bca7bea16a0cd806' as 'src/secp256k1'
Update src/secp256k1 subtree to upstream libsecp256k1 v0.3.0