[lld] [lld][ELF] Add --why-live flag (inspired by Mach-O) (PR #127112)

[via llvm-commits]

github-actions[bot] wrote:

<!--LLVM CODE FORMAT COMMENT: {clang-format}-->


:warning: C/C++ code formatter, clang-format found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

``````````bash
git-clang-format --diff 8942d5ee6f73f00b9ccb1a1e4c27d4ff43fc41fe e9a07435750994c86fbeead34482eca98562b26c --extensions cpp,h -- lld/ELF/Config.h lld/ELF/Driver.cpp lld/ELF/MarkLive.cpp
``````````

</details>

<details>
<summary>
View the diff from clang-format here.
</summary>

``````````diff
diff --git a/lld/ELF/MarkLive.cpp b/lld/ELF/MarkLive.cpp
index 96593e2fb1..219c9d4a6c 100644
--- a/lld/ELF/MarkLive.cpp
+++ b/lld/ELF/MarkLive.cpp
@@ -45,7 +45,7 @@ using namespace lld::elf;
 
 namespace {
 
-using SecOffset = std::pair<InputSectionBase*, unsigned>;
+using SecOffset = std::pair<InputSectionBase *, unsigned>;
 
 // Something that can have an independent reason for being live.
 using LiveObject = std::variant<InputSectionBase *, Symbol *, SecOffset>;

``````````

</details>


https://github.com/llvm/llvm-project/pull/127112