FLB_{IN,OUT}_KAFKA is enabled by default since v2.1.5, causing compile errors if no c++ support. These patches allow the Kafka plugin to be build without C++. Fixes: - http://autobuild.buildroot.net/results/d63/d638390da721eb3bdfcc7a4229114b492aaead99/ - http://autobuild.buildroot.net/results/709/70960056479eab860e94eed993566fcb78c4dbbe/ - http://autobuild.buildroot.net/results/366/3667126ee954f927f83ccfbaae3c6fb8ebd07dbb/ - http://autobuild.buildroot.net/results/9bd/9bd090216b9a8005fc3d020a9c0adf5e825bea59/ - ... Signed-off-by: Thomas Devoogdt <thomas@devoogdt.com> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>