[llvm] [IR] Do not set `none` for function uwtable (PR #93387)

[Fangrui Song via llvm-commits]

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@@ -654,7 +654,8 @@ class LLVM_EXTERNAL_VISIBILITY Function : public GlobalObject,
     return getUWTableKind() != UWTableKind::None;
   }
   void setUWTableKind(UWTableKind K) {
-    addFnAttr(Attribute::getWithUWTableKind(getContext(), K));
+    if (K != UWTableKind::None)
+      addFnAttr(Attribute::getWithUWTableKind(getContext(), K));
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MaskRay wrote:

If we add `else { removeFnAttr }` , a unittest will probably be needed

https://github.com/llvm/llvm-project/pull/93387