AP_Math: split CRCs from checksums #37935

Job	Run time
build (base)	9m 8s
build-gcc-heli	8m 35s
build (clang)	10m 47s
autotest-heli (sitltest-heli)	13m 39s
autotest (sitltest-copter-tests1a)	11m 17s
autotest (sitltest-copter-tests1b)	13m 32s
autotest (sitltest-copter-tests1c)	14m 55s
autotest (sitltest-copter-tests1d)	13m 16s
autotest (sitltest-copter-tests1e)	12m 41s
autotest (sitltest-copter-tests2a)	13m 30s
autotest (sitltest-copter-tests2b)	1h 4m 11s
	3h 5m 31s

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