Make fill independent on code unit type #5688

Job	Run time
mingw (mingw64)	4m 13s
mingw (ucrt64)	3m 56s
build (windows-2019, Win32, v142, 17, Debug)	1m 15s
build (windows-2019, Win32, v142, 17, Release)	2m 4s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	1m 20s
build (windows-2019, Win32, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 17s
build (windows-2019, x64, v140, 14, Debug)	1m 19s
build (windows-2019, x64, v140, 14, Release)	2m 10s
build (windows-2019, x64, v141, 17, Debug)	1m 52s
build (windows-2019, x64, v141, 17, Release)	2m 14s
build (windows-2019, x64, v142, 17, Debug)	1m 59s
build (windows-2019, x64, v142, 17, Release)	2m 24s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Debug)	2m 3s
build (windows-2019, x64, v142, 17, -DBUILD_SHARED_LIBS=ON, Release)	2m 24s
build (windows-2019, x64, v142, 20, Debug)	2m 12s
build (windows-2019, x64, v142, 20, Release)	2m 23s
build (windows-2022, x64, v143, Debug, 20)	2m 2s
	38m 7s

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