const go/parser.PackageClauseOnly

3 uses

	go/parser (current package)
		interface.go#L52: 	PackageClauseOnly    Mode             = 1 << iota // stop parsing after package clause
		parser.go#L2870: 	if p.mode&PackageClauseOnly == 0 {

	golang.org/x/tools/go/packages
		golist_overlay.go#L439: 	f, err := parser.ParseFile(token.NewFileSet(), filename, contents, parser.PackageClauseOnly) // TODO(matloob): reuse fileset?