Add cross-language LLVM CFI support to the Rust compiler

This commit adds cross-language LLVM Control Flow Integrity (CFI)
support to the Rust compiler by adding the
`-Zsanitizer-cfi-normalize-integers` option to be used with Clang
`-fsanitize-cfi-icall-normalize-integers` for normalizing integer types
(see https://reviews.llvm.org/D139395).

It provides forward-edge control flow protection for C or C++ and Rust
-compiled code "mixed binaries" (i.e., for when C or C++ and Rust
-compiled code share the same virtual address space). For more
information about LLVM CFI and cross-language LLVM CFI support for the
Rust compiler, see design document in the tracking issue #89653.

Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and
-Zsanitizer-cfi-normalize-integers, and requires proper (i.e.,
non-rustc) LTO (i.e., -Clinker-plugin-lto).

compiler/rustc_session/src/options.rs

@@ -1659,6 +1659,12 @@ options! {
         "immediately print bugs registered with `delay_span_bug` (default: no)"),
     sanitizer: SanitizerSet = (SanitizerSet::empty(), parse_sanitizers, [TRACKED],
         "use a sanitizer"),
+    sanitizer_cfi_canonical_jump_tables: Option<bool> = (Some(true), parse_opt_bool, [TRACKED],
+        "enable canonical jump tables (default: yes)"),
+    sanitizer_cfi_generalize_pointers: Option<bool> = (None, parse_opt_bool, [TRACKED],
+        "enable generalizing pointer types (default: no)"),
+    sanitizer_cfi_normalize_integers: Option<bool> = (None, parse_opt_bool, [TRACKED],
+        "enable normalizing integer types (default: no)"),
     sanitizer_memory_track_origins: usize = (0, parse_sanitizer_memory_track_origins, [TRACKED],
         "enable origins tracking in MemorySanitizer"),
     sanitizer_recover: SanitizerSet = (SanitizerSet::empty(), parse_sanitizers, [TRACKED],
@@ -1704,6 +1710,8 @@ options! {
                  file which is ignored by the linker
         `single`: sections which do not require relocation are written into object file but ignored
                   by the linker"),
+    split_lto_unit: Option<bool> = (None, parse_opt_bool, [TRACKED],
+        "enable LTO unit splitting (default: no)"),
     src_hash_algorithm: Option<SourceFileHashAlgorithm> = (None, parse_src_file_hash, [TRACKED],
         "hash algorithm of source files in debug info (`md5`, `sha1`, or `sha256`)"),
     #[rustc_lint_opt_deny_field_access("use `Session::stack_protector` instead of this field")]