Fix KTX2 header initialization in included BasisU code #543

Job	Run time
windows (windows-latest, v143, x64, NO, Debug,Release, ON, ON, OpenGL+Vulkan, ON, ON, ON, ON, YES...	22m 54s
windows (windows-latest, v143, x64, NO, Release, OFF, OFF, OFF, OFF, OFF, OFF, NO, OFF, OFF)	4m 9s
windows (windows-latest, v143, x64, NO, Release, OFF, OFF, OFF, OFF, OFF, OFF, NO, OFF, ON)	4m 26s
windows (windows-latest, v143, x64, NO, Release, OFF, OFF, OFF, OFF, OFF, OFF, NO, ON, ON)	5m 49s
windows (windows-latest, CLangCL, x64, NO, Debug,Release, ON, ON, OpenGL+Vulkan, ON, ON, ON, ON, ...	26m 48s
windows (windows-latest, CLangCL, x64, NO, Release, OFF, OFF, OFF, OFF, OFF, OFF, NO, OFF, OFF)	6m 52s
windows (windows-latest, CLangCL, x64, NO, Release, OFF, OFF, OFF, OFF, OFF, OFF, NO, OFF, ON)	6m 51s
windows (windows-latest, CLangCL, x64, NO, Release, OFF, OFF, OFF, OFF, OFF, OFF, NO, ON, ON)	6m 42s
windows (windows-latest, CLangCL, x64, ONLY, Visual Studio 17 2022)	58s
windows (windows-2019, v142, x64, Debug,Release, ON, ON, OpenGL+Vulkan, ON, ON, ON, ON, NO, ON, O...	23m 44s
windows (windows-latest, CLangCL, arm64, Debug,Release, ON, ON, OpenGL, OFF, ON, ON, ON, YES, Vis...	31m 17s
	2h 20m 30s

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