build: Default to VULKANSC=ON #237

Job	Run time
mingw	4m 20s
Ubuntu Backcompat	10m 5s
check_vvl	1m 40s
linux (address sanitizer, debug, robinhood ON )	19m 8s
linux (address sanitizer, release, robinhood ON )	8m 26s
linux (thread sanitizer, debug, robinhood ON )	18m 3s
windows (amd64)	14m 55s
linux (thread sanitizer, release, robinhood ON )	5m 11s
windows (amd64_x86)	14m 50s
linux (address sanitizer, release, robinhood OFF )	10m 26s
	1h 47m 4s

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