dea9b1d1e0 Re-export base64 when enabled (Alekos Filini)
Pull request description:
`base64` used to be exported until commit 23ee0930c7 which removed the `pub extern crate` declaration.
ACKs for top commit:
Kixunil:
ACK dea9b1d1e0
apoelstra:
ACK dea9b1d1e0
Tree-SHA512: 2f32b6676aab9881bab9eb0ae61910ec0d4b60cb17c8a7bf8155ec4a13e50abce0061b52f4e81b106b938e99cb68329d027291c1702213cfa2a46734ebadb488