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/messages.ftl

@@ -35,7 +35,15 @@ session_cannot_mix_and_match_sanitizers = `-Zsanitizer={$first}` is incompatible
 
 session_cannot_enable_crt_static_linux = sanitizer is incompatible with statically linked libc, disable it using `-C target-feature=-crt-static`
 
-session_sanitizer_cfi_enabled = `-Zsanitizer=cfi` requires `-Clto`
+session_sanitizer_cfi_requires_lto = `-Zsanitizer=cfi` requires `-Clto`, `-Clto=thin`, or `-Clinker-plugin-lto`
+
+session_sanitizer_cfi_canonical_jump_tables_requires_cfi = `-Zsanitizer-cfi-canonical-jump-tables` requires `-Zsanitizer=cfi`
+
+session_sanitizer_cfi_generalize_pointers_requires_cfi = `-Zsanitizer-cfi-generalize-pointers` requires `-Zsanitizer=cfi` or `-Zsanitizer=kcfi`
+
+session_sanitizer_cfi_normalize_integers_requires_cfi = `-Zsanitizer-cfi-normalize-integers` requires `-Zsanitizer=cfi` or `-Zsanitizer=kcfi`
+
+session_split_lto_unit_requires_lto = `-Zsplit-lto-unit` requires `-Clto`, `-Clto=thin`, or `-Clinker-plugin-lto`
 
 session_unstable_virtual_function_elimination = `-Zvirtual-function-elimination` requires `-Clto`