sys/linux: add basic examples of vusb variants #17569

Job	Run time
build	3m 1s
aux	4m 35s
dashboard	2m 35s
race	10m 5s
old	6m 54s
gvisor	3m 57s
arch (presubmit_arch_linux)	10m 56s
arch (presubmit_arch_freebsd)	6m 10s
race_dashboard	3m 24s
arch (presubmit_arch_windows)	3m 42s
arch (presubmit_arch_darwin)	3m 44s
arch (presubmit_arch_openbsd)	3m 47s
arch (presubmit_arch_netbsd)	3m 49s
arch (presubmit_arch_executor)	3m 19s
	1h 9m 58s

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