[clang] [clang] Stub out gcc_struct attribute (PR #71148)

[Erich Keane via cfe-commits]

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@@ -3635,6 +3635,13 @@ def MSStruct : InheritableAttr {
   let SimpleHandler = 1;
 }
 
+def GCCStruct : InheritableAttr {
+  let Spellings = [GCC<"gcc_struct">];
+  let Subjects = SubjectList<[Record]>;
+  let Documentation = [Undocumented];
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erichkeane wrote:

Documentation required.

https://github.com/llvm/llvm-project/pull/71148