This change enables `zig build-lib` and friends to take a response file
of command line arguments, for example:

```sh
zig build-lib @args.rsp
```

Which effectively does the same thing as this in Bash:

```sh
zig build-lib $(cat args.rsp)
```

Being able to use a file for arguments is important as one can quickly
exceed the 32 KiB limit that Windows imposes on arguments to a process.

Helps #10693

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>