fx add-host-test

向 args.gn 添加 GN 标签并进行重新生成

usage: fx add-host-test //foo/bar //foo/baz

Adds the labels to `host_test_labels` and regen.
This is useful when `fx test` tells you to add a target to the build,
but you have some custom args set in `args.gn`, so do not want to run
`fx set` to overwrite those args.

add-host-test 源代码