com.docker.slirp: on startup, retry the database connection
com.docker.slirp: on startup, retry the database connection

When com.docker.slirp became database-aware, a startup race was created
because com.docker.db and com.docker.slirp are started at the same
time.

This patch makes com.docker.slirp startup more robust by retrying
the database connection every 0.1s for 5s.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@docker.com>

djs55/vpnkit,samoht/vpnkit,djs55/vpnkit,djs55/vpnkit