[llvm] [TOOLS][DWARFDUMP][DWARF] Print full DIE offset for a CU or local TU (PR #121877)

[Greg Clayton via llvm-commits]

clayborg wrote:

We could pass a `DWARFContext *` into the dumping function which can  be used if it isn't `NULL`? Then we have access to the DWARFContext so we can grab CUs and if they are skeleton CUs, we can get the non skeleton CU Die. If the .dwo or .dwp file is available, you will be able to get the right CU and print the right offset, if it isn't we shouldn't print out a DIE offset. Do we want to indicate to the user that we can't calculate the DIE offset without the .dwo/.dwp file?

For foreign TUs we need to find the right one that matches the DW_AT_dwo_name in the foreign TU. If the .dwo names don't match, then we need to print that this entry is not valid instead of printing a DIE offset. 

All of this will be super helpful when tracking down issues, so this is worth doing!

https://github.com/llvm/llvm-project/pull/121877