DroneCAN: added FlexDebug support #40932

Job	Run time
build-gcc-heli	5m 11s
build (base)	5m 15s
build (clang)	5m 39s
autotest (sitltest-copter-tests1a)	8m 24s
autotest (sitltest-copter-tests1b)	10m 10s
autotest (sitltest-copter-tests1c)	12m 28s
autotest (sitltest-copter-tests1d)	9m 45s
autotest (sitltest-copter-tests1e)	9m 53s
autotest (sitltest-copter-tests2a)	10m 6s
autotest (sitltest-copter-tests2b)	31m 29s
autotest-heli (sitltest-heli)	10m 13s
	1h 58m 33s

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