[clang] [Clang][Sema] placement new initializes typedef array with correct size (PR #83124)

[David Blaikie via cfe-commits]

dwblaikie wrote:

Simplified a bit more:
```
template <typename T>
void f1() {
  int (*x)[1] = new int[1][1]; // fails
}
template void f1<char>();
void f2() {
  int (*x)[1] = new int[1][1]; // passes
}
```
https://godbolt.org/z/MhaYbvefG - yeah seems pretty clear this is a regression. Compiles with GCC, fails with clang, and the non-dependent context passes with either.

https://github.com/llvm/llvm-project/pull/83124