Update to upstream version 0.20.22
Details:
- Upstream changelog see: https://raw.githubusercontent.com/MusicPlayerDaemon/MPD/v0.20.22/NEWS
- gcc_pure patch for src/input/Error.hxx was adopted upstream This is a confirmed bug in LLVM before 7.0, see https://bugs.llvm.org/show_bug.cgi?id=32611
MFH: 2018Q4