[llvm] [LLVM][DWARF] Add compilation directory and dwo name to TU in dwo section (PR #74909)

[Alexander Yermolovich via llvm-commits]

ayermolo wrote:

> Looks OK.
> 
> We could potentially do this in all DWARF versions, not just >= 5. (seems relatively harmless to do it in the v4 extension version of Split DWARF?)
> 
> & could you get some measurements, especially .o file size (or more specifically, .o .debug_info size) for a clang build with this patch/without this patch? Just so we know what sort of growth to expect.

We can, but then it just increases complexity, slightly, + more tests modified, probably, since then there will be else statement for GNU_dwo_name.

OK, will see what increase in clang is.

https://github.com/llvm/llvm-project/pull/74909