All the 9legacy patches are available on http://9legacy.org/patch.html.
Most of the compiler changes consist in keeping them in sync with Charles' updates, available on https://bitbucket.org/plan9-from-bell-labs/plan9. The (partial) C99 changes were done long ago, in March 2006 and before. https://github.com/0intro/plan9/commits/master/sys/src/cmd/cc -- David du Colombier
