update cc code: tokenpool-client, tokenpool-master, jobserver-fifo

[milahu]

currently, the cc folder has an old version of stefanb2's topic-tokenpool-master branch
see also https://github.com/milahu/ninja/tree/stefanb2/topic-tokenpool-master-old

the new versions should be merged:

• Add GNU make jobserver client support ninja-build/ninja#1140
  • https://github.com/stefanb2/ninja/tree/topic-issue-1139-squashed
  • https://github.com/milahu/ninja/tree/stefanb2/topic-tokenpool-client
• Add GNU make jobserver master support ninja-build/ninja#2260
  • https://github.com/stefanb2/ninja/tree/topic-issue-1139-part-2-tokenpool-master
  • https://github.com/milahu/ninja/tree/stefanb2/topic-tokenpool-master
• Add GNU make jobserver style "fifo" support ninja-build/ninja#2263
  • https://github.com/stefanb2/ninja/tree/topic-issue-1139-part-3-jobserver-fifo
  • https://github.com/milahu/ninja/tree/stefanb2/topic-jobserver-fifo