RFR(XS): 8229450: C2 compilation fails with assert(found_sfpt) failed

[Roland Westrelin]

> I made mistake yesterday. I missed ' -XX:+UseCountedLoopSafepoints'.

+UseCountedLoopSafepoints is the default and it's the only reasonable
one so I don't think it's necessary to list it explicity. Regarding the
code change: there is no need to mention bug numbers in the code. The
source control system keeps track of that. There are existing cases
where bugs are mentioned but they usually are in much older changes as
it's no longer the current practice.

My testing came back clean. You can consider this reviewed by me but you
need another reviewer. I don't think we can count Tobias as a review (at
least not yet). Once it's reviewed, I'll sponsor it.

Roland.