Google Code migration

Ben Hutchingsrequested to merge
bwh/google-code-migration into master

Google Code shut down in 2015. Update mirroring of all the projects formerly hosted there.

Most of them converted from Subversion or Mercurial to Git, so introduce new mirrors for them and mark the old ones as obsolete.

Depends on !53 (merged).

Edited by Ben Hutchings

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