Add rustfmt from relibc and apply it with cargo fmt

src/percpu.rs

@@ -1,5 +1,4 @@
-use crate::LogicalCpuId;
-use crate::context::switch::ContextSwitchPercpu;
+use crate::{context::switch::ContextSwitchPercpu, LogicalCpuId};
 
 /// The percpu block, that stored all percpu variables.
 pub struct PercpuBlock {
@@ -11,7 +10,6 @@ pub struct PercpuBlock {
 
     // TODO: Put mailbox queues here, e.g. for TLB shootdown? Just be sure to 128-byte align it
     // first to avoid cache invalidation.
-
     #[cfg(feature = "profiling")]
     pub profiling: Option<&'static crate::profiling::RingBuffer>,
 }