* Buffered file output is now periodically flushed by a background
thread
* The MultiprocessRollingFileAppender did not work
* Properly prevent undefined behaviour when an appender is deleted
without being closed
* Prevent abnormal termination on exit when using a static NDC/MDC
variable
* Support for std::experimental::optional (in the standard library
used by gcc 5.4)
* Overhead reduction of upto 60% sending logging events to an appender
* Statistics on the AsyncAppender's queue length
* [Fuzz tests](@ref fuzzing) along with Google OSS-Fuzz
* MSYS2/MINGW build errors
* `thread_local` problems in MSYS2/MINGW
* A potential 'use after free' fault when using AsyncAppender
OBS-URL: https://build.opensuse.org/package/show/devel:libraries:c_c++/librdkafka?expand=0&rev=42
