[NFC] Minor fix to tryEmitAbstract type in EmitCXXNewAllocSize (#123433)

In EmitCXXNewAllocSize, when handling a constant array size, we were
calling tryEmitAbstract with the type of the object being allocated rather
than the expected type of the array size. This worked out because the
allocated type was always a pointer and tryEmitAbstract only ends up
using the size of the type to extend or truncate the constant, and in this
case the destination type should be size_t, which is usually the same
width as the pointer. This change fixes the type, but it makes no
functional difference with the current constant emitter implementation.

Author: andykaylor

clang/lib/CodeGen/CGExprCXX.cpp

@@ -732,8 +732,8 @@ static llvm::Value *EmitCXXNewAllocSize(CodeGenFunction &CGF,
   // Emit the array size expression.
   // We multiply the size of all dimensions for NumElements.
   // e.g for 'int[2][3]', ElemType is 'int' and NumElements is 6.
-  numElements =
-    ConstantEmitter(CGF).tryEmitAbstract(*e->getArraySize(), e->getType());
+  numElements = ConstantEmitter(CGF).tryEmitAbstract(
+      *e->getArraySize(), (*e->getArraySize())->getType());
   if (!numElements)
     numElements = CGF.EmitScalarExpr(*e->getArraySize());
   assert(isa<llvm::IntegerType>(numElements->getType()));