feat(sys): allow passing more cmake flags #281

Job	Run time
rustfmt	8s
build (ubuntu-latest, stable)	36s
clippy (ubuntu-latest, stable)	48s
build (ubuntu-latest, nightly)	55s
clippy (ubuntu-latest, nightly)	58s
build (windows-latest, stable)	3m 16s
clippy (windows-latest, stable)	2m 14s
build (windows-latest, nightly)	2m 47s
clippy (windows-latest, nightly)	3m 19s
build (macos-latest, stable)	42s
clippy (macos-latest, stable)	37s
build (macos-latest, nightly)	1m 0s
clippy (macos-latest, nightly)	55s
	18m 15s

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