Use 'go install' instead of 'go build' to generate all commands at the same time.

'go build' compiles the packages but discards the results if multiple packages specified. So the expected binaries can't be generated in output/go with current HEAD.

The following copied from 'go help build':

When the command line specifies a single main package,
build writes the resulting executable to output.
Otherwise build compiles the packages but discards the results,
serving only as a check that the packages can be built.