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

[via llvm-commits]

mgschossmann wrote:

I have now found a small program (https://godbolt.org/z/eKcvY6caW) that, when compiled with gcc, results in a .debug_loclists section containing such a base type reference, which currently crashes dwarfdump.

I can try to add a test case which is based on this.

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