libphoenix: fix mutexing in pthread_create #902

Job	Run time
call-ci / build (armv7a7-imx6ull-evk)	1m 33s
call-ci / build (armv7a9-zynq7000-qemu)	2m 20s
call-ci / build (armv7a9-zynq7000-zedboard)	1m 56s
call-ci / build (armv7a9-zynq7000-zturn)	1m 32s
call-ci / build (armv7m4-stm32l4x6-nucleo)	1m 54s
call-ci / build (armv7m7-imxrt105x-evk)	2m 12s
call-ci / build (armv7m7-imxrt106x-evk)	1m 41s
call-ci / build (armv7m7-imxrt117x-evk)	2m 6s
call-ci / build (host-generic-pc)	1m 13s
call-ci / build (ia32-generic-pc)	1m 39s
call-ci / build (ia32-generic-qemu)	1m 31s
call-ci / build (riscv64-generic-qemu)	1m 21s
call-ci / build (riscv64-generic-spike)	1m 32s
call-ci / build (sparcv8leon3-gr716-mini)	1m 33s
call-ci / test EMU (armv7a9-zynq7000-qemu)	7m 7s
call-ci / test HW (armv7a7-imx6ull-evk)	3m 57s
call-ci / test HW (armv7m7-imxrt106x-evk)	1m 54s
call-ci / test EMU (host-generic-pc)	1m 9s
call-ci / test HW (armv7m7-imxrt117x-evk)	2m 33s
call-ci / test EMU (ia32-generic-qemu)	5m 6s
call-ci / test HW (armv7a9-zynq7000-zedboard)	5m 1s
call-ci / test EMU (riscv64-generic-qemu)	2m 1s
call-ci / test HW (armv7m4-stm32l4x6-nucleo)	11m 8s
call-ci / tests-summary	54s
call-ci / send-notification	0s
	1h 4m 53s

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