Function print_where_clause

pub(crate) fn print_where_clause(
    gens: &Generics,
    cx: &Context<'_>,
    indent: usize,
    ending: Ending,
) -> Option<impl Display>

• The Generics from which to emit a where-clause.
• The number of spaces to indent each line with.
• Whether the where-clause needs to add a comma and newline after the last bound.