Use parallel syncs.

Also, wait until syncing is done to write the tree.
Also, only delete the out tree.

Change-Id: I7d6c144c8ea5a702b74c827dd5879107baa4c145
1 file changed
tree: dc6cef4efb0d93348de172acf8574dc49d07125b
  1. gps/
  2. CleanSpec.mk
  3. generate-blob-lists.sh