Linker plugins should be aware of --defsym during symbol resolution

[Cary Coutant]

>> Are you intentionally excluding symbols defined in scripts? It seems
>> to me that they should be treated the same as --defsym.
>
> Ok,  it is just that I do not have test cases with scripts and I
> haven't looked into creating a few yet.  If this is as simple as
> omitting the is_defsym() check then I can make that change.

Yes, that's all it is.

Your patch is OK with those changes.

-cary