MB-5307 Flush pending config_changed messages in compaction daemon.
MB-5307 Flush pending config_changed messages in compaction daemon.

To avoid potentially excessive compaction daemon restarts.

Change-Id: I3882c962022dcb79eb0d72ffd0a2c36e43b1e0d0
Reviewed-on: http://review.couchbase.org/17191
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

membase/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,t3rm1n4l/ns_server,membase/ns_server,vzasade/ns_server,daverigby/ns_server,ceejatec/ns_server,pavel-blagodov/ns_server,membase/ns_server,nimishzynga/ns_server,daverigby/ns_server,ceejatec/ns_server,nimishzynga/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,membase/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,daverigby/ns_server,ceejatec/ns_server,mschoch/ns_server,mschoch/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,daverigby/ns_server,ceejatec/ns_server,ceejatec/ns_server,vzasade/ns_server,mschoch/ns_server,ceejatec/ns_server,nimishzynga/ns_server,daverigby/ns_server,pavel-blagodov/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,vzasade/ns_server,membase/ns_server,membase/ns_server