[LLD][COFF] Add more `--time-trace` tags for ThinLTO linking (#156471)

In order to better see what's going on during ThinLTO linking, this PR
adds more profile tags when using `--time-trace` on a `lld-link.exe`
invocation.

After PR, linking `clang.exe`:

<img width="3839" height="2026" alt="Capture d’écran 2025-09-02 082021"
src="https://github.com/user-attachments/assets/bf0c85ba-2f85-4bbf-a5c1-800039b56910"
/>

Linking a custom (Unreal Engine game) binary gives a completly
different picture, probably because of using Unity files, and the sheer
amount of input files (here, providing over 60 GB of .OBJs/.LIBs).

<img width="1940" height="1008" alt="Capture d’écran 2025-09-02 102048"
src="https://github.com/user-attachments/assets/60b28630-7995-45ce-9e8c-13f3cb5312e0"
/>

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp
index 70d3641..30b5e48 100644
--- a/llvm/lib/IR/Module.cpp
+++ b/llvm/lib/IR/Module.cpp
@@ -44,6 +44,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/RandomNumberGenerator.h"
+#include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/VersionTuple.h"
 #include <cassert>
 #include <cstdint>
@@ -478,6 +479,7 @@ Error Module::materializeAll() {
 }
 
 Error Module::materializeMetadata() {
+  llvm::TimeTraceScope timeScope("Materialize metadata");
   if (!Materializer)
     return Error::success();
   return Materializer->materializeMetadata();