Add blank lines after module-level //! comments.

Most modules have such a blank line, but some don't. Inserting the blank
line makes it clearer that the `//!` comments are describing the entire
module, rather than the `use` declaration(s) that immediately follows.

compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs

@@ -4,6 +4,7 @@
 //!
 //! For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler,
 //! see design document in the tracking issue #89653.
+
 use rustc_data_structures::base_n::ToBaseN;
 use rustc_data_structures::base_n::ALPHANUMERIC_ONLY;
 use rustc_data_structures::base_n::CASE_INSENSITIVE;

compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/mod.rs

@@ -3,6 +3,7 @@
 //!
 //! For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler,
 //! see design document in the tracking issue #89653.
+
 use rustc_data_structures::fx::FxHashMap;
 use rustc_middle::bug;
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, TypeFoldable};

compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs

@@ -3,6 +3,7 @@
 //!
 //! For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler,
 //! see design document in the tracking issue #89653.
+
 use rustc_hir as hir;
 use rustc_hir::LangItem;
 use rustc_middle::bug;

compiler/rustc_sanitizers/src/cfi/typeid/mod.rs

@@ -3,6 +3,7 @@
 //!
 //! For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler,
 //! see design document in the tracking issue #89653.
+
 use bitflags::bitflags;
 use rustc_middle::ty::{Instance, Ty, TyCtxt};
 use rustc_target::abi::call::FnAbi;

compiler/rustc_sanitizers/src/kcfi/typeid/mod.rs

@@ -3,6 +3,7 @@
 //!
 //! For more information about LLVM KCFI and cross-language LLVM KCFI support for the Rust compiler,
 //! see the tracking issue #123479.
+
 use rustc_middle::ty::{Instance, InstanceKind, ReifyReason, Ty, TyCtxt};
 use rustc_target::abi::call::FnAbi;
 use std::hash::Hasher;