[llvm] [LV][EVL] Support reduction idioms using tail folding with EVL. (PR #90184)

[Florian Hahn via llvm-commits]

================
@@ -57,6 +58,11 @@ class VectorBuilder {
     return RetType();
   }
 
+  // Helper function for creating VP intrinsic call.
----------------
fhahn wrote:

nit: use `///` for doc-comment

https://github.com/llvm/llvm-project/pull/90184