This is the merge of 2 patches:
Pass the DWARFUnit to DWARFDebugLine::getFileNameByIndex().
This way it can query the compilation dir when it is referenced (when a file references directory index 0, it refers to the compilation dir).
and:
[dwarfdump] Implement extraction of file information referenced in .debug_info.
This patch pretty prints the contents of the DW_AT_decl_file, DW_AT_call_file, DW_AT_decl_line and DW_AT_call line attributes.
Drop the const on the passed DWARFUnit to be able to call getLineTableForUnit (the line table construction is lazy, thus the getter might modify the Unit).