waf: allow any custom build option to be specified in waf configure #42133

Job	Run time
build (stm32f7, chibios, 10)	15m 55s
build (stm32h7, chibios, 10)	14m 16s
build (fmuv2-plane, chibios, 10)	7m 47s
build (periph-build, chibios, 10)	14m 29s
build (iofirmware, chibios, 10)	4m 39s
build (CubeOrange-bootloader, chibios, 10)	3m 31s
build (fmuv3-bootloader, chibios, 10)	3m 20s
build (revo-bootloader, chibios, 10)	3m 22s
build (stm32h7-debug, chibios, 10)	9m 19s
build (fmuv3, chibios, 10)	15m 26s
build (revo-mini, chibios, 10)	12m 31s
build (MatekF405-Wing, chibios, 10)	13m 10s
build (CubeOrange-ODID, chibios, 10)	10m 11s
build (CubeRedPrimary-bootloader, chibios, 10)	3m 31s
build (configure-all, chibios, 10)	12m 32s
build (build-options-defaults-test, chibios, 10)	25m 55s
build (signing, chibios, 10)	11m 19s
build (CubeOrange-PPP, chibios, 10)	8m 51s
build (CubeOrange-EKF2, chibios, 10)	8m 39s
build (SOHW, chibios, 10)	14m 29s
build (Pixhawk6X-PPPGW, chibios, 10)	5m 28s
build (new-check, chibios, 10)	15m 7s
	3h 53m 47s

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