[llvm] [X86] Reimplement bundle alignment mode (PR #175830)

[Fangrui Song via llvm-commits]

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@@ -489,9 +489,12 @@ class MCBoundaryAlignFragment : public MCFragment {
   /// is not meaningful before that.
   uint64_t Size = 0;
 
+  bool AlignToEnd;
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MaskRay wrote:

Comment. `= false` and remove the initializer at the ctor

https://github.com/llvm/llvm-project/pull/175830