This update for sccache fixes the following issues:

Update to version 0.2.13~git474.6628e1f:

  * New entry in ServerStartup enum to indicate AddrInUse Error (#840)
  * Revert "Bump to tiny-http 0.7.0 (#830)" because it caused a regression, #846.
  * Include -fsanitizer-blacklist in common_args
  * Consume sanitizer blacklist as extra hash in msvc (#842)
  * In case we fail to read the compressed content from the cache, treat the failure as a forced
    recache. This prevents us from failing build jobs unconditionally if cache entries are corrupt
    (or in case of other sporadic failures), in which case we should continue on with
    force-recompiling and recaching. (#836)
  * Bump to tiny-http 0.7.0 (#830)
  * Modify logging to use SCCACHE_LOG. (#822)
  * Implement `g++` and `clang++` behavior when used on a `.c` input file. Fixes #803 (#818)
  * clang: Allow chrome plugin arguments (#817)
  * Add known caveats section to readme (#815)

- Configure features to generate sccache-dist for distributed builds.
- Add systemd unit files for builder and scheduler and example configs.

- Add --features=all to allow all cache backends to be used.

- Add support for obs cargo vendor to make packaging easier.
  * osc service ra - now can update the source files.