Reformat use declarations.

The previous commit updated `rustfmt.toml` appropriately. This commit is
the outcome of running `x fmt --all` with the new formatting options.

compiler/rustc_data_structures/src/work_queue.rs

@@ -1,6 +1,7 @@
+use std::collections::VecDeque;
+
 use rustc_index::bit_set::BitSet;
 use rustc_index::Idx;
-use std::collections::VecDeque;
 
 /// A work queue is a handy data structure for tracking work left to
 /// do. (For example, basic blocks left to process.) It is basically a