Temurin-build: Support build in gcc 9

Related https://github.com/AdoptOpenJDK/openjdk-build/issues/451.

We don't have gcc 9 installed on the machines so this is likely an openjdk-infrastructure first and then openjdk-build issue to get it configured. @karianna Can you move this over to inf?

@M-Davies I wold suggest that unless there's a decision on this (which would require openjdk-build adjustments) this is the correct home for it, with a separate issue if we choose to install it)

@joeyleeeeeee97 We build most of them on gcc 7.5 now. Is there a specific thing that you are aware of which is advantageous when build with gcc 9 - I presume there's something you're aware of since you haven't picked gcc 10 :-)

I can do issue transfers the whole day :joy:

@M-Davies I wold suggest that unless there's a decision on this (which would require openjdk-build adjustments) this is the correct home for it, with a separate issue if we choose to install it)

@joeyleeeeeee97 We build most of them on gcc 7.5 now. Is there a specific thing that you are aware of which is advantageous when build with gcc 9 - I presume there's something you're aware of since you haven't picked gcc 10 :-)

Yes. We find higher version of gcc brings significant benefits on some microbenchmarks. The reason we chose gcc9 is mostly that gcc 10 haven't be widely used in Alibaba. :)

Yes. We find higher version of gcc brings significant benefits on some microbenchmarks. The reason we chose gcc9 is mostly that gcc 10 haven't be widely used in Alibaba. :)

Thanks for the info. In that case I think we should certainly look at setting up Linux/x64 with gcc-9 for the Dragonwell builds only initially :-)

@joeyleeeeeee97 Are the microbenchmarks that show up the improvements available in the open?

@joeyleeeeeee97 Are the microbenchmarks that show up the improvements available in the open?

Spec tests(specjbb2015) performance is better, for a specific number and cases we could do this once we got a gcc9 dragonwell to compare with its gcc7 version. :)