"Fixes #2866Fixes#2894
Changes gossip propagation to allow "atomic" grouping of values to ensure
their respective order.
Modifies gossip bootstrap startup to potentially wait longer in cases
where stabilization (messages done) takes time, to avoid data loss
in repair."
* 'calle/gossip' of github.com:scylladb/seastar-dev:
gossip: wait for stabilized gossip on bootstrap
gossiper: Prevent race condition in propagation
utils::to_string: Add printers for pairs+maps
utils::in: Add helper type for perfect forwarding initializer lists