[clang] [Sparc][clang] Match GCC's SPARC V8 vector return convention (PR #222264)

[Folkert de Vries via cfe-commits]

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@@ -50,3 +50,77 @@ t(long double _Complex a)
 {
     return 0;
 }
+
+typedef char v4i8 __attribute__((vector_size(4)));
+typedef char v8i8 __attribute__((vector_size(8)));
+typedef char v16i8 __attribute__((vector_size(16)));
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folkertdev wrote:

maybe add `v1i32` and `v2i32` variants too?

https://github.com/llvm/llvm-project/pull/222264