RFR: 8236714: enable link-time section-gc for linux to remove unused code

[Baesken, Matthias]

Hi Erik, I did not notice  slowdowns in our night makes .

Looking at a specific  test machine  I use  (x86_64,  build JOBS hardwired  set  to 12 )   I  get around  6 minutes build time  with and without the feature .

( but you have to take into account  that  the  link-time section-gc   on  x86_64    in my patch is only enabled  for the smaller JDK libs and not libjvm.so  )  

Best regards, Matthias


> 
> Given the discussion regarding lto on hotspot and the extreme increased
> build time, have you noticed any difference in build times with this patch?
> 
> /Erik
>