[NFCI]Prospective fix for MVSC Build bot-

The previous code hits an assert inside the MSVC compiler version 16.8,
    which is our minimum supported version.  This patch looks on godbolt
    like it avoids this crash, so submitting it to hopefully unbreak the
    bot.

clang/lib/Sema/SemaOpenACCClauseAppertainment.cpp

@@ -34,8 +34,7 @@ class AccClauseSet {
   }
 
 public:
-  constexpr AccClauseSet(
-      const std::initializer_list<OpenACCClauseKind> &Clauses)
+  constexpr AccClauseSet(std::initializer_list<OpenACCClauseKind> Clauses)
       : Data(0) {
     for (OpenACCClauseKind C : Clauses)
       setBit(C);