girocco: delay initial project gc until not empty
When a project is initially created touch a .delaygc
file. As long as the .delaygc file exists, gc will
be postponed.
The file is removed by forking a non-empty repo,
cloning a non-empty remote repo, fetching new refs
at update time and receiving new refs from the client.
This allows the first gc of a new project (and the
corresponding bundle/bitmap build) to take place soon
after the initial content is pushed rather than waiting
until it's time for gc to run on the project again.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>