[llvm] [LLVM][DWARF] Change .debug_names abbrev to be an index (PR #81200)

[Felipe de Azevedo Piovezan via llvm-commits]

https://github.com/felipepiovezan approved this pull request.

>This allows for tools like LLDB to access it in constant time.

I don't think this is true: the spec does not require the table to be monotonically increasing. So LLDB either needs to first check if all entries are neatly organized, or just build a map anyway.

The big motivation for this patch is the space savings: the debug_names section will be much smaller as most abbreviations now fit in 1 byte

https://github.com/llvm/llvm-project/pull/81200