Fully expired sstable is not added to compacting set, meaning it's not actually
compacted, but it's kept in a list of sstables which incremental compaction
uses to check if any sstable can be replaced.
Incremental compaction was unconditionally removing expired sstable from compacting
set, which led to segfault because end iterator was given.
The fix is about changing sstable_set::erase() behavior to follow standard one
for erase functions which will works if the target element is not present.
Fixes#4085.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20190130163100.5824-1-raphaelsc@scylladb.com>
(cherry picked from commit 930f8caff9)
3172cc6bac