Fix warnings from MSVC #6009

Job	Run time
mingw (mingw64)	4m 12s
build (windows-2019, Win32, v142, 17, Debug)	1m 57s
build (windows-2019, Win32, v142, 17, Release)	2m 52s
mingw (ucrt64)	4m 19s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	2m 20s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	3m 2s
build (windows-2019, x64, v140, 14, Debug)	1m 58s
build (windows-2019, x64, v140, 14, Release)	2m 7s
build (windows-2019, x64, v141, 17, Debug)	2m 13s
build (windows-2019, x64, v141, 17, Release)	2m 55s
build (windows-2019, x64, v142, 17, Debug)	2m 20s
build (windows-2019, x64, v142, 17, Release)	2m 33s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 9s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 54s
build (windows-2019, x64, v142, 20, Debug)	1m 37s
build (windows-2019, x64, v142, 20, Release)	2m 54s
build (windows-2022, x64, v143, Debug, 20)	2m 0s
	43m 22s

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