// The argument list is nil for no parens on the definition; otherwise a list of
// formal argument names.
func (in *Input) macroDefinition(name string) ([]string, []Token) {
	prevCol := in.Stack.Col()
	tok := in.Stack.Next()
	if tok == '\n' || tok == scanner.EOF {
		return nil, nil // No definition for macro
	}
	var args []string
	// The C preprocessor treats
	//	#define A(x)
	// and