Remove unused variable 's' and 'e' in ktxUpgrader::main #182

Job	Run time
windows (windows-latest, v143, x64, Debug,Release, ON, ON, OpenGL+Vulkan, ON, ON, ON, YES, ON, OFF)	24m 17s
windows (windows-latest, v143, x64, Release, OFF, OFF, OFF, OFF, OFF, NO, OFF, OFF)	4m 5s
windows (windows-latest, v143, x64, Release, OFF, OFF, OFF, OFF, OFF, NO, OFF, ON)	3m 1s
windows (windows-latest, v143, x64, Release, OFF, OFF, OFF, OFF, OFF, NO, ON, ON)	3m 40s
windows (windows-latest, CLangCL, x64, Debug,Release, ON, ON, OpenGL+Vulkan, ON, ON, ON, YES, ON,...	32m 14s
windows (windows-latest, CLangCL, x64, Release, OFF, OFF, OFF, OFF, OFF, NO, OFF, OFF)	4m 35s
windows (windows-latest, CLangCL, x64, Release, OFF, OFF, OFF, OFF, OFF, NO, OFF, ON)	4m 30s
windows (windows-latest, CLangCL, x64, Release, OFF, OFF, OFF, OFF, OFF, NO, ON, ON)	5m 21s
windows (windows-2019, v142, x64, Debug,Release, ON, ON, OpenGL+Vulkan, ON, ON, ON, NO, ON, OFF, ...	27m 14s
windows (windows-latest, CLangCL, arm64, Debug,Release, ON, ON, OFF, ON, ON, ON, YES, Visual Stud...	17m 45s
	2h 6m 42s

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