[llvm] [llvm-dwarfdump] Add a null-check in `prettyPrintBaseTypeRef`. (PR #93156)

[David Blaikie via llvm-commits]

dwblaikie wrote:

Rather than a checked-in binary, could you use assembly code instead? Perhaps using the new https://llvm.org/docs/TestingGuide.html#elaborated-tests functionality

https://github.com/llvm/llvm-project/pull/93156