FLUME-3320 Fix:Taildir source reset position bug

[winway]

Taildir source has chance to reset position to 0 incorrectly, so data while be duplicated. When log rotate happens just in time so that f and tf are not the same file in between code.

f (f.length() < tf.getPos()) {
    logger.info("Pos " + tf.getPos() + " is larger than file size! "
        + "Restarting from pos 0, file: " + tf.getPath() + ", inode: " + inode);
    tf.updatePos(tf.getPath(), inode, 0);
}

[rgoers]

This looks like it is superseded by #368.

[rgoers]

Superceded by #368