PATCH: Add discriminator support to bfd, objdump and addr2line

[Cary Coutant]

>> I have added a new interface bfd_find_nearest_line_discriminator() to
>> also return the discriminator (which was previously being ignored when
>> reading the dwarf), and also added support to print non-zero
>> discriminators along with the source position information from objdump
>> and addr2line.
>>
>> Tested on x86_64-unknown-linux-gnu. Ok for trunk?
>
> OK.

Thanks, Alan. I've committed the patch for Teresa.

-cary