AP_GPS: Moving base yaw fixes #1110

Job	Run time
build (stm32f7, chibios, 10)	18m 50s
build (stm32h7, chibios, 10)	16m 23s
build (fmuv2-plane, chibios, 10)	7m 21s
build (periph-build, chibios, 10)	23m 27s
build (iofirmware, chibios, 10)	2m 7s
build (CubeOrange-bootloader, chibios, 10)	1m 22s
build (fmuv3-bootloader, chibios, 10)	1m 55s
build (revo-bootloader, chibios, 10)	1m 38s
build (stm32h7-debug, chibios, 10)	8m 59s
build (fmuv3, chibios, 10)	21m 4s
build (revo-mini, chibios, 10)	21m 8s
build (MatekF405-Wing, chibios, 10)	24m 56s
build (CubeOrange-ODID, chibios, 10)	12m 57s
build (CubeRedPrimary-bootloader, chibios, 10)	1m 49s
build (configure-all, chibios, 10)	6m 39s
build (build-options-defaults-test, chibios, 10)	28m 29s
build (signing, chibios, 10)	14m 12s
	3h 33m 16s

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