build: Default to VULKANSC=ON #238

Job	Run time
mingw	3m 46s
Ubuntu Backcompat	9m 56s
check_vvl	1m 27s
linux (address sanitizer, debug, robinhood ON )	33m 48s
linux (address sanitizer, release, robinhood ON )	16m 4s
windows (amd64)	15m 17s
windows (amd64_x86)	15m 10s
linux (thread sanitizer, debug, robinhood ON )	42m 7s
linux (thread sanitizer, release, robinhood ON )	22m 33s
linux (address sanitizer, release, robinhood OFF )	15m 11s
	2h 55m 19s

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