[lld] [LLD][COFF] Add support for custom DOS stub (PR #122561)

[Hans Wennborg via llvm-commits]

================
@@ -115,6 +115,7 @@ struct Configuration {
   enum ManifestKind { Default, SideBySide, Embed, No };
   bool is64() const { return llvm::COFF::is64Bit(machine); }
 
+  std::unique_ptr<MemoryBuffer> stub;
----------------
zmodem wrote:

nit: maybe `dosStub` would be clearer?

https://github.com/llvm/llvm-project/pull/122561