* Do not throw away commitlog segments on disk size overflow.
Issue a flush request (i.e. calculate RP we want to free unto,
and for all dirty CF:s, do a request).
"Abstracted" as registerable callback. I.e. DB:s responsibility
to actually do something with it.
* Fixes#247
* Re-introduce test_allocation_failure, but allow for the "failure" to not
happen. I.e. if run with low memory settings, the test will check that
allocation failure is graceful. With lots of memory it will check partial
write.
Origin
* Note: removed commitlog_test:test_allocation_failure because with
segments limited to 4GB -> mutation limited to 2GB, actually forcing
a fail is not guaranteed or even likely.
