stdliblist: Fix for Go 1.18 by replicating stdlib

The stdliblist operation that the gopackagesdriver relies on fails on
Go 1.18rc1 with the following error:

```
external/go_sdk/src/crypto/elliptic/p256_asm.go:24:12: pattern p256_asm_table.bin: cannot embed irregular file p256_asm_table.bin
```

We see this failure because Bazel builds a symlink tree of the GOROOT run
`go list` with. However, since [CL 380475][1], the Go standard library uses
`go:embed` to embed a file in `crypto/elliptic`, but `go:embed` does not
support symlinks.

[1]: https://go.dev/cl/380475

Fix this by having stdliblist copy the relevant portions of the GOROOT to
run `go list` with. This matches [what the stdlib action does][2].

[2]: https://github.com/bazelbuild/rules_go/blob/e9a7054ff11a520e3b8aceb76a3ba44bb8da4c94/go/tools/builders/stdlib.go#L54-L57

Resolves bazelbuild#3080

go/tools/builders/stdliblist.go

@@ -158,19 +158,22 @@ func stdliblist(args []string) error {
 		return err
 	}
 
+	execRoot := abs(".")
+	if err := replicate(os.Getenv("GOROOT"), execRoot, replicatePaths("src", "pkg/tool", "pkg/include")); err != nil {
+		return err
+	}
+
 	// Ensure paths are absolute.
 	absPaths := []string{}
 	for _, path := range filepath.SplitList(os.Getenv("PATH")) {
 		absPaths = append(absPaths, abs(path))
 	}
 	os.Setenv("PATH", strings.Join(absPaths, string(os.PathListSeparator)))
-	os.Setenv("GOROOT", abs(os.Getenv("GOROOT")))
+	os.Setenv("GOROOT", execRoot)
 	// Make sure we have an absolute path to the C compiler.
 	// TODO(#1357): also take absolute paths of includes and other paths in flags.
 	os.Setenv("CC", abs(os.Getenv("CC")))
 
-	execRoot := abs(".")
-
 	cachePath := abs(*out + ".gocache")
 	defer os.RemoveAll(cachePath)
 	os.Setenv("GOCACHE", cachePath)