oeqa/core/threaded: Add OEStreamLoggerThreaded class
The OEStreamLoggerThreaded overrides OEStreamLogger to redirect
the PyUnit output to a logger.
Instead of log every line when comes the OEStreamLoggerThreaded
will buffer the PyUnit output and write everything at end of every
suite execution to don't have mixed suite outputs.
[YOCTO #11450]
Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
