Tiny comment fixes.

compiler/rustc_incremental/src/persist/fs.rs

@@ -53,7 +53,7 @@
 //! ## Synchronization
 //!
 //! There is some synchronization needed in order for the compiler to be able to
-//! determine whether a given private session directory is not in used any more.
+//! determine whether a given private session directory is not in use any more.
 //! This is done by creating a lock file for each session directory and
 //! locking it while the directory is still being used. Since file locks have
 //! operating system support, we can rely on the lock being released if the

compiler/rustc_incremental/src/persist/load.rs

@@ -1,4 +1,4 @@
-//! Code to save/load the dep-graph from files.
+//! Code to load the dep-graph from files.
 
 use crate::errors;
 use rustc_data_structures::memmap::Mmap;

compiler/rustc_incremental/src/persist/work_product.rs

@@ -11,7 +11,8 @@ use rustc_session::Session;
 use std::fs as std_fs;
 use std::path::Path;
 
-/// Copies a CGU work product to the incremental compilation directory, so next compilation can find and reuse it.
+/// Copies a CGU work product to the incremental compilation directory, so next compilation can
+/// find and reuse it.
 pub fn copy_cgu_workproduct_to_incr_comp_cache_dir(
     sess: &Session,
     cgu_name: &str,