Fix DeckLink native control commands #298

Job	Run time
build-macos-no-brew-Qt6 (clang-9)	5m 50s
build-macos-brew-Qt6 (clang-9)	3m 35s
build-linux (gcc-9)	5m 21s
build-linux-Qt6 (gcc-9)	6m 26s
build-macos-brew (clang-9)	3m 9s
build-macos-no-brew (clang-9)	5m 14s
build-windows-mingw (5.15.*)	14m 20s
build-windows-mingw-Qt6 (6.5.*, qtmultimedia qt5compat)	17m 50s
build-windows-vs (5.15.*)	11m 11s
build-windows-vs-Qt6 (6.3.*, qtmultimedia qt5compat)	17m 12s
	1h 30m 8s

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