cmd/link Command Line Interface

The go command and any other Go-aware build systems invoke cmd/link
to link a collection of packages into a single binary. By default, cmd/link will
present the same interface it does today:

	cmd/link main.a

produces a file named a.out, even if cmd/link does so by invoking the host
linker in external linking mode.

By default, cmd/link will decide the linking mode as follows: if the only