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

[antoine moynault via cfe-commits]

antmox wrote:

hello, instantiate-new-placement-size.cpp also fails here :
https://lab.llvm.org/buildbot/#/builders/188/builds/44501

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