Miley Cyrus, 20, is the latest in a long line of child music stars eager to leave their youth behind and be seen as artists with adult appeal. With “Bangerz,” out Monday (7), Cyrus tries once and forever more to leave Hannah Montana in the rear view mirror. Here”s a look at some other music artists who first hit stardom at a very young age and how they fared in their bid to navigate through some awkward years to become mainstream stars and remain on the Billboard Hot 100.