[llvm] [LLVM][DWARF] Add support for .gnu_debuglink (PR #77715)

[Alexander Yermolovich via llvm-commits]

================
@@ -127,6 +127,9 @@ class DWARFContext : public DIContext {
 
   std::unique_ptr<const DWARFObject> DObj;
 
+  /// Binary containing debug information after objcopy --only-keep-debug
+  object::OwningBinary<object::ObjectFile> GnuLink;
----------------
ayermolo wrote:

> I feel like I'm missing something. As I understand it, replacing the stripped binary with an OKD binary would remove sections that are necessary for full symbolication, general debugging, and proper program execution (.symtab, .strtab, .shstrtab in my simple tests). If we replaced the stripped binary, how would we deal with those sections?

.symtab is actually copied
![image](https://github.com/llvm/llvm-project/assets/43973793/c81040e7-286b-48f1-a2a0-3f75c8b7c836)

That being said the .eh_frame is not. :/

https://github.com/llvm/llvm-project/pull/77715