[clang] [llvm] [PAC] Fix address discrimination for type info vtable pointers (PR #102199)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic commented:

I think you should be able to avoid constructing the initializer twice if you restructure the code a bit to just construct the global before the call to BuildVTablePointer.  I added GlobalVariable::replaceInitializer because I was looking at this review: it lets you construct the global before the initializer, without having to do awkward things with RAUW.

https://github.com/llvm/llvm-project/pull/102199