Install GCC-9 into ROCm builders (#53459)
Summary:
Should prevent intermittent internal compiler errors reported in https://bugs.launchpad.net/ubuntu/+source/gcc-7/+bug/1917830
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53459
Reviewed By: izdeby
Differential Revision: D26870602
Pulled By: malfet
fbshipit-source-id: 1e90bb0d33736d01a696f80fc981aedcf7e3b639
