[llvm] [Bitcode][NFC] Add abbrev for FUNC_CODE_DEBUG_LOC (PR #146497)

[Orlando Cazalet-Hyams via llvm-commits]

OCHyams wrote:

Or we just bump it to 5 bits as @nikic says, I don't have a strong opinion either way - https://github.com/llvm/llvm-project/pull/146717 for the abbrev removal.

https://github.com/llvm/llvm-project/pull/146497