add basic example of justfile (#345) #2081

Job	Run time
Build	4m 14s
Build vendored (vendored-openssl, g3proxy)	3m 10s
Build vendored (vendored-openssl, g3bench)	1m 45s
Build vendored (vendored-openssl, g3tiles)	2m 12s
Build vendored (vendored-openssl, g3fcgen)	1m 48s
Build vendored (vendored-openssl, g3mkcert)	1m 40s
Build vendored (vendored-openssl, g3keymess)	2m 51s
Build vendored (vendored-tongsuo, g3proxy)	2m 55s
Build vendored (vendored-tongsuo, g3bench)	1m 28s
Build vendored (vendored-tongsuo, g3tiles)	1m 55s
Build vendored (vendored-tongsuo, g3fcgen)	1m 30s
Build vendored (vendored-tongsuo, g3mkcert)	1m 14s
Build vendored (vendored-tongsuo, g3keymess)	1m 45s
Build vendored (vendored-aws-lc, g3proxy)	4m 16s
Build vendored (vendored-aws-lc, g3bench)	2m 54s
Build vendored (vendored-aws-lc, g3tiles)	3m 10s
Build vendored (vendored-aws-lc, g3fcgen)	2m 56s
Build vendored (vendored-aws-lc, g3mkcert)	2m 24s
Build vendored (vendored-aws-lc, g3keymess)	3m 9s
Build vendored (vendored-boringssl, g3proxy)	4m 10s
Build vendored (vendored-boringssl, g3bench)	2m 44s
Build vendored (vendored-boringssl, g3tiles)	3m 4s
Build vendored (vendored-boringssl, g3fcgen)	2m 58s
Build vendored (vendored-boringssl, g3mkcert)	2m 1s
Build vendored (vendored-boringssl, g3keymess)	2m 38s
Build vendored (vendored-c-ares, g3proxy)	4m 14s
	1h 9m 5s

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