[clang] [NFC][Clang] Add `setExprs` overload to reduce some code duplication (PR #139749)

[Erich Keane via cfe-commits]

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@@ -492,7 +492,7 @@ class OpenACCSelfClause final
 
 /// Represents a clause that has one or more expressions associated with it.
 class OpenACCClauseWithExprs : public OpenACCClauseWithParams {
-  MutableArrayRef<Expr *> Exprs;
+  MutableArrayRef<Expr *> Storage;
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erichkeane wrote:

THIS change actually doesn't make sense.  This is actually supposed to be the `Exprs` that this `WithExprs` refers to.

https://github.com/llvm/llvm-project/pull/139749