RFR: 8234525: enable link-time section-gc for linux s390x to remove unused code

[Baesken, Matthias]

Hi Martin , 

> Hi Matthias and Erik,
> 
> I also think this is an interesting option.
> 
> I like the idea to generate smaller libraries. In addition to that, I could also
> imagine building with -Os (size optimized) by default and only select -O3 for
> performance critical files (e.g. C2's register allocation, some gc code, ...).
> 

This is a good idea .   However I would like to look into this separately in another change .
 ( Maybe  there should also be a configure setting  to select for size vs. speed optimization )


> If we want to go into such a direction for all linux platforms and want to use
> this s390 only change as some kind of pipe cleaner, I think this change is fine
> and can get pushed.

Yes , that  was my intention.
Erik, may I add you as  a reviewer too  ?

Best regards, Matthias


> Otherwise, I think building s390 differently and not intending to do the same
> for other linux platforms would be not so good.
> 
> We should only make sure the exported symbols are set up properly to avoid
> that this optimization throws out too much.
> 
> My 50 Cents.
> 
> Best regards,
> Martin
>