"Don't cry" or "Don't you cry"
Solution 1:
Don't you cry can have several meanings.
It can mean, no, not you (maybe, too?)
"There — don't you cry no more. I can't abear to see you cry." He was blinking himself.
or, emphasizing an imperative
Your daddy's rich/ And your mamma's good lookin'/ So hush little baby/ Don't you cry.
or, just a gentle personalizing and softening of the imperative.
Hush, little baby, don't you cry, Mamma's gonna sing you a lullabye