core: Add accessor to the tag associated with a dwarf_tag To isolate dwarf_tag->tag so that at some point we can avoid two allocations for tag + dwarf_tag and instead get just one chunk of memory that we can go from one to the other and thus elliminate the tag->priv and dwarf_tag->tag pointers. Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>