MediaScanner: Fix path mismatch in code that check for missing files in postScan()

    private boolean inScanDirectory(String path, String[] directories) {

        for (int i = 0; i < directories.length; i++) {

            if (path.startsWith(directories[i])) {

            String directory = directories[i];

            if (mExternalStoragePath != null && directory.equals(mMediaStoragePath)) {

                // database paths use external storage prefix

                directory = mExternalStoragePath;

            }

            if (path.startsWith(directory)) {

                return true;

            }

        }