classes/buildhistory: do git garbage collection after committing
We don't normally perform any operations (such as "git pull") that
trigger "git gc --auto", thus garbage collection never happens which
means performance of accessing the repository degrades noticeably over
time. Add an explicit "git gc --auto" to clean things up when needed.
Thanks to Elijah Newren and Ross Burton for suggesting this.
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
