Getting inline function information

[Adam Jocksch <ajocksch at redhat dot com>]

After conversing with Roland this afternoon, I think I've figured out 
the way we should be approaching this problem. It looks like we need to 
do the following things for each PC in the stack frame returned from 
libunwind:

1) get the scopes for that pc using dwarf_getscopes (already wrapped).
2) Started at the innermost scope, work our way backwards and check for 
a Dwarf_Die with the DW_TAG_inlined_subroutine tag on it. Attributes 
attached to this tag may give us more information about the call state 
of the inlined code. You can get the Dwarf tag by using dwarf_tag.

He also suggested taking a look at 
elfutils/src/addr2line.c:print_dwarf_function (which I have yet to do 
but will do shortly) for more information. It looks like the things that 
need to be accomplished to get this working are
a) Wrap dwarf_tag
b) Wrap whatever we need to get any/all relevant attributes out of the 
dwarf_tag (this may very well end up becoming a part of step (a) ).

Hopefully I should be able to get started on this sometime this week, so 
if anyone has any questions/comments/criticisms please feel free to 
respond :)

Adam