[gtest] fix build error when building posix (#11289) #247

Job	Run time
channel-manager-csl	3m 13s
expects	31m 11s
packet-verification-low-power	8m 51s
packet-verification-1-1-on-1-4	10m 51s
thread-1-4-posix	9m 25s
thread-1-4-gcc-m32	11m 30s
thread-1-4-gcc-m64	12m 7s
thread-1-4-clang-m32	10m 2s
thread-1-4-clang-m64	10m 20s
upload-coverage	36s
	1h 48m 6s

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