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

[Baesken, Matthias]

Hi David, sure we can introduce a way to switch this on/off.
There is already something similar for the link-time optimization (flto) , see the feature 

JvmFeatures.gmk
180 ifeq ($(call check-jvm-feature, link-time-opt), true)
190 ifeq ($(call check-jvm-feature, link-time-opt), false)

hotspot.m4
29 static-build link-time-opt aot jfr"
502 JVM_FEATURES_link_time_opt="link-time-opt"


Should we have  "link-time-gc"  additionally to   " link-time-opt"  ?   (however it  would  be a  bit misleading   that it is a "JVM" feature , but except linux s390x  it is only changing the build of the JDK libs) .

Best regards, Matthias



> 
> Hi Matthias,
> 
> I have reservations about turning this on by default and with no way to
> control it. This seems like it should be something you have to opt-in to
> initially while we gain some experience with it and ensure there are no
> unexpected side-effects. After that it could be enabled by default.
>