[clang] [clang][bytecode] Check for unknown size array pointers in InitField* (PR #154689)

[Shafik Yaghmour via cfe-commits]

================
@@ -1652,6 +1655,9 @@ bool InitFieldActivate(InterpState &S, CodePtr OpPC, uint32_t I) {
   const Pointer &Ptr = S.Stk.peek<Pointer>();
   if (!CheckRange(S, OpPC, Ptr, CSK_Field))
     return false;
+  if (!CheckArray(S, OpPC, Ptr))
----------------
shafik wrote:

I feel like `CheckArray` is really `DiagnoseIfArrayOfUnknownSize` a mouthful for sure. 

https://github.com/llvm/llvm-project/pull/154689