libc: string.h: add cmp functions tests #2383

Job	Run time
call-ci / build (armv7a7-imx6ull-evk)	1m 30s
call-ci / build (armv7a9-zynq7000-qemu)	1m 59s
call-ci / build (armv7a9-zynq7000-zedboard)	1m 27s
call-ci / build (armv7a9-zynq7000-zturn)	1m 32s
call-ci / build (armv7m4-stm32l4x6-nucleo)	1m 17s
call-ci / build (armv7m7-imxrt106x-evk)	1m 31s
call-ci / build (armv7m7-imxrt117x-evk)	1m 29s
call-ci / build (host-generic-pc)	1m 14s
call-ci / build (ia32-generic-pc)	1m 13s
call-ci / build (ia32-generic-qemu)	1m 13s
call-ci / build (riscv64-generic-qemu)	1m 27s
call-ci / build (riscv64-generic-spike)	1m 4s
call-ci / run tests on emulators (armv7a9-zynq7000-qemu)	6m 21s
call-ci / run tests on emulators (host-generic-pc)	1m 7s
call-ci / run tests on emulators (ia32-generic-qemu)	4m 19s
call-ci / run tests on hardware (armv7a7-imx6ull-evk)	3m 23s
call-ci / run tests on hardware (armv7m7-imxrt106x-evk)	1m 42s
call-ci / run tests on hardware (armv7m7-imxrt117x-evk)	2m 10s
call-ci / run tests on hardware (armv7a9-zynq7000-zedboard)	5m 6s
call-ci / run tests on hardware (armv7m4-stm32l4x6-nucleo)	8m 28s
call-ci / notify ci team using e-mail	0s
	49m 32s

Provide feedback