0046bb8ad8 Fix usage of cfg(rust_1_53) (Tobin C. Harding)
c3450f3913 Remove stale usage of doc(cfg) (Tobin C. Harding)
Pull request description:
These build cfg options are not features, fix broken usage. And remove stale docsrs attribute while we are at it. Bad rust-bitcoin devs.
Found while reviewing #1870
ACKs for top commit:
apoelstra:
ACK 0046bb8ad8
Kixunil:
ACK 0046bb8ad8
Tree-SHA512: 7053affef6654ff203c93590bf081e165f019feb040aa8c55259ffe4e15eaf0e7522f6e5a4f6f62e8f578420b0313f4b7b17c46b741b7fcfd05750e5c5976589