This commit refactors TruncIndex to make it possible to add container
ids to the TruncIndex without updating the Suffixarray.
This is useful during the Docker daemon's startup when we don't want to
update the Suffixarray for every container we add.
Add continues to function like before.
Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Upstream-commit: 219b7ae8b526bb5e6d0e27176308db71438a002f
Component: engine