[llvm] [llvm-pdbutil] Fix register enum field dumping/parsing (PR #82299)

[via llvm-commits]

nikitalita wrote:

I'm sorry, but it's been long enough since this was opened that I no longer have the pdb files that caused this bug, and I don't remember the fields in which the register ID popped up

https://github.com/llvm/llvm-project/pull/82299