AP_Rally: support altitude frames #25940

Job	Run time
build (chibios, Durandal)	40m 6s
build (chibios, MatekF405)	27m 22s
build (chibios, KakuteF7)	24m 0s
build (chibios, MatekH743-bdshot)	29m 53s
build (chibios, Pixhawk1-1M)	31m 14s
build (chibios, MatekF405-CAN)	3m 3s
build (chibios, DrotekP3Pro)	2m 20s
build (chibios, Hitec-Airspeed)	5m 44s
build (chibios, f103-GPS)	6m 29s
build (disco, armhf)	32m 33s
	3h 22m 44s

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