Test a profiled GHC build on CI

During my work on !7797 (closed) I identified multiple bugs triggering segfaults when I used a profiled ghc to compile something while profiling was enabled.

That is to say only when I ran something like _profiled_ghc/stage1/bin/ghc foo.hs -O +RTS -p

Were it not for my careful local testing we would have long merged this patch, segfaults and it. It may be worthwhile to test a profiled ghc on CI in a nightly job or similar to avoid something like this from making it into master.

As a side benefit we could perhaps collect the profiles generated by this for more detailed performance comparisons over time.