-gccgoprefix prefix
		The -fgo-prefix option to be used with gccgo.
	-gccgopkgpath path
		The -fgo-pkgpath option to be used with gccgo.
	-gccgo_define_cgoincomplete
		Define cgo.Incomplete locally rather than importing it from
		the "runtime/cgo" package. Used for old gccgo versions.
	-godefs
		Write out input file in Go syntax replacing C package
		names with real values. Used to generate files in the

	if canonical, ok := w.importMap[fromDir][fromPath]; ok {
		name = canonical
	}

	pkg := w.imported[name]
	if pkg != nil {
		if pkg == &importing {
			log.Fatalf("cycle importing package %q", name)
		}
		return pkg, nil
	}
	w.imported[name] = &importing

	// Determine package files.
	dir := w.importDir[name]
	if dir == "" {
		dir = filepath.Join(w.root, filepath.FromSlash(name))
	}