Eliminate some PHP warnings. #3720

Job	Run time
libs-build	4m 54s
libs-build	6m 18s
apps-build	13m 17s
apps-build	13m 17s
libs-cmake-build	10m 57s
libs-cmake-build	10m 57s
client-armv6-build	2m 40s
client-armv6-build	2m 40s
client-arm-build	3m 37s
client-arm-build	3m 37s
client-arm64-build	4m 6s
client-arm64-build	4m 6s
client-x86-build	4m 14s
client-x86-build	4m 14s
client-x86_64-build	4m 11s
client-x86_64-build	4m 11s
manager-build (assembleRelease)	3m 44s
manager-build (assembleRelease)	3m 44s
manager-build (assembleXiaomi_release)	3m 57s
manager-build (assembleXiaomi_release)	3m 57s
manager-build (assembleArmv6_release)	3m 52s
manager-build (assembleArmv6_release)	3m 52s
manager-build (jacocoTestReportDebug)	5m 52s
manager-build (jacocoTestReportDebug)	5m 52s
	2h 12m 6s

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