Put attributes and enum variants on different lines

[topecongiro]

Closes #2389.

We still put attributes and fields on the same line inside variant (I hope I am using the right terminologies). For example,

// Attributes on the same line
pub enum Entry<'a, K: 'a, V: 'a> {
    Vacant(#[stable(feature = "rust1", since = "1.0.0")] VacantEntry<'a, K, V>),
    Occupied(#[stable(feature = "rust1", since = "1.0.0")] OccupiedEntry<'a, K, V>),
}

// Attributes on the different line
pub enum Entry<'a, K: 'a, V: 'a> {
    #[stable(feature = "rust1", since = "1.0.0")]
    Vacant(VacantEntry<'a, K, V>),
    #[stable(feature = "rust1", since = "1.0.0")]
    Occupied(OccupiedEntry<'a, K, V>),
}

[RReverser]

Hmm these two examples have different semantics. Did you mean to put attributes outside of enum body in the first case?

[nrc]

Thanks!